Menachot 84b ~On the Content of our Dreams

מנחות פד,ב

רבי יוחנן מאי טעמא? אמר רבי אלעזר רבי יוחנן חזאי בחלום מילתא מעלייתא אמינא

What is the reason for the ruling of Rabbi Yohanan? Rabbi Elazar said: I have an explanation of Rabbi Yohanan’s ruling and since I saw Rabbi Yohanan in a dream, I know that I am saying something correct…

Rabbi Yohanan ruled that bikkurin may never be brought using inferior fruit, but he did not give a source for his ruling. Rabbi Elazar believed that he know the source, and furthermore, he was certain he was correct because he had seen Rabbi Yochanan in a dream. Here is the explanation of one version of Rashi (and it’s not the one usually printed in the Talmud).

וכיון דגברא רבא אתחזאי לי אמינא מילתא מעלייתא אני אומר היום

Since a great man appeared to me, I will give a good explanation today

What is the significance of our dreams, and for that matter, why do we dream at all?

The Talmud ON Dreams

The Talmud contains many theories about the content of dreams and our response to them. In Berachot (10b) Rabbi Hanan taught that even if a dream appears to predict one's imminent death, the one who dreamed should pray for mercy. R. Hanan believed that dreams may contain a glimpse of the future, but that prayer is powerful enough to changes one's fate. Later in Berachot (55b), R. Yohanan suggests a different response to a distressing dream: let the dreamer find three people who will suggest that in fact the dream was a good one (a suggestion that is codified in שולחן ערוך יורה דעה 220:1).

He should say to them "I saw a good dream" and they should say to him "it is good and let it be good, and may God make it good. May heaven decree on you seven times that it will be good, and it will be good.

Shmuel, the Babylonian physician who died around 250 CE, had a unique approach to addressing the content of his own dreams. "When he had a bad dream, he would cite the verse 'And dreams speak falsely' [Zech. 10:2]. When he had a good dream he would say "are dreams false? Isn't it stated in the Torah [Numbers 12:6] 'I speak with him in a dream'?" (Berachot 55b).  In contrast, Rabbi Yonatan suggests that dreams do not predict the future: rather they reflect the subconscious (Freud would have been proud). "R. Yonatan said: a person is only shown in his dreams what he is thinking about in his heart..." (Berachot 55b).  And in Gittin (52a) we learn that Rabbi Meir believed dreams were of no consequence whatsoever: “דברי חלומות לא מעלין ולא מורידין” 

“It is of interest that two millennia separated the first detailed description of the major peripheral characteristics of dreaming from the first contemporary experimental results of brain research in this field, while only about 60 years were necessary to establish relatively solid knowledge of the basic and higher integrated neurobiological processes underlying REM sleep.”

— Gottesmann, C. The development of the science of dreaming. International Review of Neurobiology 2010. 92: 16

WHY do we dream?

Dreaming takes place during the REM (Rapid Eye Movement) stage of sleep, when there is brain activation similar to that found in waking, but muscle tone is inhibited and the eyes move rapidly. This type of sleep was only discovered in the 1950s, and since then it has been demonstrated in mammals and birds (but not yet in robots). Most adults have four or five periods of REM sleep per night, which mostly occur in 90 minute cycles. Individual REM periods may last from a few minutes to over an hour, with REM periods becoming longer the later it is in the night. 

Here are some theories about why we dream, all taken from this paper. (The author, J. Allan Hobson, directed the Laboratory of Neurophysiology at the Massachusetts Mental Health Center from 1968 to 2003. He also published more than 200 peer-reviewed articles and 10 books on sleep and dreaming. So he knows something about the physiology of sleep.) 

1. Sleep and dreaming are needed to regulate energy

Deprive a lab rat of all sleep and it will die. Deprive a lab rat of REM sleep so that it does not dream, and it too will die.  These sleep-and-dream deprived rats lost weight and showed heat seeking behavior. This suggests for animals which regulate their body temperature, sleep is needed to control both body temperature and weight. Importantly, only mammals and birds are homeothermic, and they are also the only animals which are known to have REM sleep.

2. Sleep deprivation and psychological equilibrium

Based on a number of experiments in healthy human volunteers, it has been shown that sleep and dreaming are essential to mental health. "The fact that sleep deprivation invariably causes psychological dysfunction" wrote Prof. Hobson in his review,  "supports the functional theory that the integrity of waking consciousness depends on the integrity of dream consciousness and that of the brain mechanisms of REM sleep." (When we studied Nedarim 15 we noted however, that eleven days of sleep deprivation seemed to have no ill effects in one man.) The relationship between dreaming and psychological health is rather more complicated though: monamine-oxidase inhibitors completely repress REM sleep, and yet are an effective class of antidepressants.  There appears to be a relationship between dreaming and psychological well being, but its parameters require much more study.   

3. Sleep, Dreams and Learning

In 1966 it was first suggested that REM sleep is related to the brain organizing itself.  This was later supported by studies which showed that the ability of an animal to learn a new task is diminished their REM sleep is interrupted.  Other studies show that REM sleep in humans is increased following an intensive learning period. 

“...dreaming could represent a set of foreordained scripts or scenarios for the organization of our waking experience. According to this hypothesis, our brains are as much creative artists as they are copy editors.”

— Hobson, JA. REM sleep and dreaming: towards a theory of protoconsciousness. Nature Reviews 2009.807.

A better explanation of Rabbi Elazar’s Dream in today’s daf

Perhaps the best way to understand the dream of R. Elazar is to take a look at his biography. R. Elazar (ben Padat) was a second generation amora (~3rd century C.E.) who was born in Babylon and later in his life moved to Israel. There he settled in Tiberias, where he studied at the Yeshivah of Rabbi Yohanan. The same Rabbi Yochanan about whom he dreamed. In fact R. Elazar saw R. Yohanan as his רבי מובהק - his most influential and beloved teacher. It was he who was sent to console R. Yohanan after the death of his brother-in-law, Resh Lakish (though R. Elazar failed to do so). Elsewhere, Rabbi Yohanan makes it clear that sometimes R. Elazar his student got things wrong. During a discussion about the reliability of witnesses, there is a claim that R. Yohanan had stated a certain opinion. Not so fast, said R. Yohanan. “That was stated by [my student] Elazar, but I never said such a thing” (אמר ליה זו אלעזר אמרה אני לא אמרתי דבר זה מעולם). But despite this lapse of memory, the esteem with which R. Yohanan was held by R. Elazar was remarkable:

יומא נג,א

וכד הוה בעי ר' אלעזר לסגויי הוה קא אזיל לאחוריה עד דמכסי מיניה

And when Rabbi Elazar wanted to leave his teacher, he would walk backward until he disappeared from Rabbi Yoḥanan’s sight [and only then would he walk normally, so as not to turn his back on his teacher].

The two men were close in life, and it turned out, in their deaths. In the year 278 C.E. Rabbi Yohanan died. He was briefly succeeded by R. Elazar who himself died within the year.

It is therefore no surprise at all that R. Elazar dreamed about his teacher. He probably did so often. The two seemed all but inseparable. And whatever are the scientific explanations for why we dream, we have all experienced dreaming about things that are on our mind. Just don’t ascribe to those dreams any more significance than that.

[Partial encore from here.]

Menachot 70b ~ The Chemistry of Chametz

We are about six months away from Pesach, so it is time to talk about about unleavened bread, called chametz. And it comes up in today’s daf.

מנחות ע,ב

מנא הני מילי אמר ריש לקיש אתיא לחם לחם ממצה כתיב הכא (במדבר טו, יט) והיה באכלכם מלחם הארץ וכתיב התם (דברים טז, ג) לחם עוני 

והתם גופה מנלן אמר ריש לקיש וכן תנא דבי ר' ישמעאל וכן תנא דבי ר' אליעזר בן יעקב אמר קרא (דברים טז, ג) לא תאכל עליו חמץ שבעת ימים תאכל עליו מצות לחם עוני דברים הבאים לידי חימוץ אדם יוצא בהן ידי חובתו בפסח יצאו אלו שאין באין לידי חימוץ אלא לידי סירחון

How do we know that matzah must be made from one of five species of grain [wheat, barley, oats spelt and rye]?  Reish Lakish said, and likewise a Sage of the school of Rabbi Yishmael taught, and likewise a Sage of the school of Rabbi Eliezer ben Ya’akov taught, that the verse states: “You shall eat no leavened bread with it; seven days you shall eat with it matzah, the bread of affliction” (Deuteronomy 16:3). This verse indicates that only with regard to substances that will come to a state of leavening does a person fulfill his obligation to eat matzah by eating them on Passover, provided that he prevents them from becoming leavened. This serves to exclude these foods, i.e., rice, millet, and similar grains, which, even if flour is prepared from them and water is added to their flour, do not come to a state of leavening but to a state of decay [sirḥon].

The important question we need to answer here is whether there is something fundamentally different about rice when compared to the five grain species that can become chametz. And is there any scientific support to the claim that rice spoils sooner than it ferments?

The Chemistry of bread making

To get at the answers we need to remind ourselves how plants make and consume starch. They take carbon dioxide from the atmosphere and water from the soil, and using the energy contained in sunlight (and the magic of chlorophyll) convert the two into a large sugar molecule we call starch. Plants use this starch to store and provide them with energy.

If you grind up wheat (or many other species of grain) you make flour which contains loads of starch. In addition to starch, flour contains proteins and enzymes which become important when the flour is mixed with water. Without going down a rabbit-hole of detail, here in general is what happens. First, an enzyme called beta-amylase breaks the large starch molecule down into a smaller molecule called maltose which is made up of two molecules of glucose. Another enzyme, maltase, breaks down each molecule of maltose into two molecules of glucose which is then broken down further to provide the plant with energy. Here is what it looks like:

From Lloyd, James R and Kötting, Oliver (July 2016) Starch Biosynthesis and Degradation in Plants. John Wiley & Sons, Ltd: Chichester.

If you add some yeast into that mix, a chemical reaction called fermentation occurs. Yeast, which is a fungus, consumes glucose and turns it into carbon dioxide and ethanol, which is an alcohol.

As the flour and water and yeast all mix together, two proteins in the flour called gliadin and glutenin (which are glutens) give the dough mixture its characteristic body, which strengthens the more it is mixed. The dough traps the carbon dioxide that is given off by the yeast cells, which causes the bread to rise. And that gives us the leavened bread we call chametz.

Of course when matzah is made, we do not add yeast to the dough. But there are yeast particles in the air and these will inevitably land on the dough where they will act in the same way, consuming glucose and creating carbon dioxide and alcohol. This process is much slower than when yeast is added when bread is made, but the plain dough will rise a little as a result.

The differences between grains and rice

Resh Lakish (together with those sages of the schools of Rabbi Yishmael and Rabbi Eliezer ben Ya’akov) claim that unlike grains, rice does not ferment when water is added to it. Instead it spoils. That’s why it may be eaten on Passover (unless of course you are an Ashkenazi Jew, in which case you still can’t eat it, but for another reason we’re not going to get into). Is this in fact the case?

I know next to nothing about plant biology. But Dr Angus Murphy does. He is Professor and Chair of the Department of Plant Science at the University of Maryland, and wrote the textbook on plant physiology. Dr. Murphy was kind enough to have a long chat with me over the phone and he agreed with the suggestion that grains and rice do very different things when mixed with water. The wheat seed is surrounded by the endosperm, which is itself covered by the aluerone layer. This aleurone is rich in amylase which as you recall is needed to breakdown starch into glucose (which is eaten by yeast which releases carbon dioxide and alcohol which causes the dough to rise…) However (most species of) rice do not contain this aleurone layer. So they have very little amylase, which means that it takes them a much longer time to convert starch into glucose. In fact it takes so long that by the time there is enough yeast in the dough for it to start to rise, bacteria in the air will have colonized the mixture and started breaking down the proteins in the dough. And that protein breakdown is what makes the mixture spoil, and which is what the Talmud calls סירחון. To conclude, Professor Murphy thought that the Talmud’s description of the difference between grain and rice was firmly based in plant biology.

The fine print and the final verdict

Distribution of variou types of amylases in rice grains. (Beta-Amylase activity was expressed in terms of maltose mg liberated in 3 min at 30°C by 1 g of ground rice samples.) From Ryu Shinke, Hiroshi Nishira & Narataro Mugibayashi. Types of Amylases in Rice Grains. Agricultural and Biological Chemistry 1973; 37:10, 2437-2438

Of course things are a little more complicated than that. (They always are.) Different kinds of wheat flour contain different amounts of amylase. Fine bleached white flour contains less amylase than say whole wheat flour, because the aleurone layer in whole wheat flour has not been broken down. Similarly, different species of rice contain different amounts of amylase, so that while standard white rice has very little, brown rice has considerably more. During talmudic times, the wheat flour would have been far less processed than any of the flour we would use today. As a result it would contain more amylase, and would have risen faster than would today’s four-water mixtures.

But as a rule of thumb, the Talmud is, biochemically speaking, spot on. When mixed with water, the five species of grain from which matzah may be made do undergo fermentation even without the addition of yeast, while rice will spoil long before the fermentation process becomes noticeable.

Menachot 64b ~ Cursed Be He Who Raises Swine

Today we are going to talk about pigs. But before we get into it, here is some important background, courtesy of the Jewish historian of the first century, Josephus.

From here.

Following the death of their father Alexander Yannai in the first century B.C.E. two brothers, Hyrcanus and Aristobulus fought over which would ascend to the Hasmonean throne. Both appealed to Rome (which turned out to be a very bad idea) and in 63 B.C.E. the military leader Pompey turned up to sort things out. He backed Hyrcanus, who was the Cohen Gadol, (high priest) at the time, and who had been originally named as the heir. Pompey captured Aristobulus and took him off to Rome, and he let Hyrcanus remain as the Cohen Gadol. But Pompey refused to Hyrcanus become king. And that is how the Romans came to Jerusalem, or as Josephus put it “we lost our liberty, and became subject to the Romans.” OK. Now here is the relevant part in tomorrow’s Daf Yomi:

מנחות סד, ב 

תנו רבנן כשצרו מלכי בית חשמונאי זה על זה והיה הורקנוס מבחוץ ואריסטובלוס מבפנים בכל יום ויום היו משלשלין להן דינרין בקופה ומעלין להן תמידין היה שם זקן אחד שהיה מכיר בחכמת יוונית לעז להם בחכמת יוונית אמר להן כל זמן שעסוקין בעבודה אין נמסרין בידכם למחר שלשלו להן דינרין בקופה והעלו להן חזיר כיון שהגיע לחצי חומה נעץ צפרניו בחומה ונזדעזעה ארץ ישראל ארבע מאות פרסה על ארבע מאות פרסה באותה שעה אמרו ארור שיגדל חזיר וארור שילמד בנו חכמת יוונית ועל אותה שעה שנינו מעשה שבא עומר מגגות צריפין ושתי הלחם מבקעת עין סוכר

The Sages taught: When the kings of the Hasmonean monarchy besieged each other [in their civil war,] Hyrcanus was outside of Jerusalem, besieging it, and Aristoblus was inside. On each and every day they would lower dinars in a box from inside the city, and those on the outside would send up animals for them to bring the daily offerings in the Temple. A certain elderly man was there [in Jerusalem] who was familiar with Greek wisdom. He communicated to those on the outside by using words understood only by those proficient in Greek wisdom. The elderly man said to them: “As long as they are engaged with the Temple service, they will not be delivered into your hands.” Upon hearing this, on the following day, when they lowered dinars in a box, they sent up a pig to them. Once the pig reached halfway up the wall, it inserted its hooves into the wall and Eretz Yisrael shuddered four hundred parasangs by four hundred parasangs. When the Sages saw this, they said at that time: Cursed is he who raises pigs, and cursed is he who teaches his son Greek wisdom…

“Alongside circumcision and Sabbath observance, the prohibition against pork is considered one of the clearest identifiers of what a Jew does and, as such, who is a Jew.”

— Jordan Rosenblum. ‘Why Do You Refuse to Eat Pork?’’ Jews, Food, and Identity in Roman Palestine. The Jewish Quarterly Review 2011. 100 (1): 95–110

Pig Husbandry in Iron Age Israel - North vs SOuth

It has been long taken as a given that archeologists could use the presence (or absence) of pig remains to distinguish a Philistine from an Israelite settlement. For example, in known Philistine sites from Iron Age I (~950-780 BCE) like Ashdod and Ekron, pig bones account for 7-19% of the animal remains, depending on which strata you are excavating. This is a much higher percentage than is found in Israelite settlements of the same period. But in 2013 this assumption was challenged by a group of top-notch Israeli archeologists (including the controversial Israel Finkelstein) who reviewed the evidence for it. They studied data from 35 sites in Israel, and found a remarkable trend. In the territory of what was once the Northern Kingdom of Israel, pig remains account for 3-7% of all animal remains. But in the Southern Kingdom of Judah, pig remains are almost absent. (The site of Aroer is a bit of an anomaly, with more than 3% pigs. However this site seems to have been a rest stop for many international travelers and so may have served a more international cuisine.) There was a dichotomy between the kingdoms of Israel and Judah that was manifest in whether they ate pork.

Sapir-Hen, L. Bar-Oz, G. Finkelstein, I. Pig Husbandry in Iron Age Israel and Judah. New Insights Regarding the Origin of the "Taboo." Zeitschrift des Deutschen Palästina-Vereins (1953-), Bd. 129, H. 1 (2013), pp. 1-20.

Why was there a rapid rise in the frequency of pigs being eaten in northern Israelite sites during Iron Age II (the period between 870 and 680 BCE)? Among the answers proposed is that “the pig taboo could have been another Judahite cultural trait that was opposed to the situation in the north, and which the authors [of the Torah] wished to impose on the entire Israelite population.” Alternatively, it may have been a result of the larger population found in the Northern Kingdom of Israel. “This process” wrote the authors of the paper Pig Husbandry in Iron Age Israel and Judah “brought about shrinkage of the open areas that are important for sheep/goat husbandry, and could have forced the Iron Age IIB population to a shift in meat production, breeding smaller herds of sheep and goats and concentrating more on pigs, which could supply large and immediate sources of meat.” In contrast, the population of the Kingdom of Judah was much smaller than that of Israel. Hence they had more open space to raise livestock.

By the way, it was the Philistines who were responsible for importing European type pigs into the Middle East. Dr Merav Meiri of the Department of Zoology at Tel Aviv University analyzed the DNA of ancient pigs in the area, and found that they possessed a European gene signature. This raises the possibility that European pigs were brought to the region by the Sea Peoples who migrated to the Levant around 900 BCE, bringing their pigs with them.

Pigs & Ancient Rome

Whether or not pigs were eaten in some parts of Biblical Israel, there is no doubt that not eating pork became synonymous with Jewish practice. In Rome, things were different. There, eating pork was widespread and enjoyed, and it was one of the most common meats associated with its residents. And as Jordan Rosenblum points out in his 2010 paper Why Do You Refuse to Eat Pork?’’ Jews, Food, and Identity in Roman Palestine swine were one of the four most common animals used for sacrifices in Rome. It was used in the most sacred rite of the Roman religion known as the suovetaurilia, in which a pig, a sheep and a goat were sacrificed to Mars, as part of a ceremony consecrating the land to the gods. According to the Roman philosopher Epictetus “the conflict between Jews and Syrians and Egyptians and Romans, [was] not over the question whether holiness should be put before everything else and should be pursued in all circumstances, but whether the particular act of eating swine’s flesh is holy or unholy.”

Our Passage in the Talmud Yerushalmi

In the Jerusalem Talmud, there is a similar description of the story told in tomorrow’s Daf Yomi, with an important difference. Can you spot it?

תלמוד ירושלמי (וילנא) מסכת ברכות פרק ד

א"ר לוי אף בימי מלכות רשעה הזאת היו משלשלין להן שתי קופות של זהב והיו מעלין להם שני כבשים ובסוף שלשלו להן ב' קופות של זהב והעלו להם שני חזירים לא הספיקו להגיע לחצי חומה עד שנעץ החזיר בחומה ונזדעזעה החומה וקפץ מ' פרסה מארץ ישראל באותה שעה גרמו העונות ובטל התמיד וחרב הבית

R. Levi said: ‘‘Also during the days of that Evil Empire [Rome], they would lower to them two baskets of gold and they would send up to them two lambs. At the end [of the siege], they lowered to them two baskets of gold and they sent up to them two pigs. They did not reach halfway up the wall when the pig stuck [its nails] in the wall and the wall shook and [the pig] jumped forty parasangs from the land of Israel. At that moment, the sins brought about both the suspension of the continual offering and the destruction of the Temple.

Here is the difference: in the Yerushalmi version the substitution of the pig for the lambs is directly linked to the destruction of Jerusalem, and not just to a general ban on the raising of pigs. “Rome’s secret weapon in times of war with the Jews” wrote Rosenblum, “is to deploy the very animal that functions as a metonym for Rome itself.”

So pigs turn out to have played more of a role in our history than would be expected. In biblical times, eating pork may have been a marker of whether you came from Israel or Judea, and pork, or at least its symbolism, played a pivotal role in the onset of the Roman attack on the Second Temple.

“Archaeologists take pigs very seriously.”

— Israel Finkelstein cited in "Who’d Import Pigs to Israel? Ancient Europeans, Researchers Say." New York Times Nov 5, 2014. A7.

Next time on Talmudology: The Chemistry of Chametz.

Menachot 42b ~ How Do You Make Techelet?

From here.

מנחות מב, ב

אמר ליה אביי לרב שמואל בר רב יהודה הא תכילתא היכי צבעיתו לה אמר ליה מייתינן דם חלזון וסמנין ורמינן להו ביורה [ומרתחינן ליה] ושקלינא פורתא בביעתא וטעמינן להו באודרא ושדינן ליה לההוא ביעתא וקלינן ליה לאודרא

Abaye said to Rav Shmuel bar Rav Yehuda: How do you dye this sky-blue wool to be used for ritual fringes? Rav Shmuel bar Rav Yehuda said to Abaye: We bring blood of a chilazon and various herbs and put them in a pot and boil them. And then we take a bit of the resulting dye in an egg shell and test it by using it to dye a wad of wool to see if it has attained the desired hue. And then we throw away that egg shell and its contents and burn the wad of wool.

It is clear from Rav Shmuel's detailed instructions that the entire process depends on one ingredient - "the blood of the chilazon" - which was used to make the dye that produced techelet and color the ritual fringes known as tzitzit. But what exactly is the chilazon? It turns out to be a rather common snail found in the Mediterranean, but for centuries the identity of the chilazon was lost. Here is the story of how it was re-discovered.

Pliny the Elder and his recipe

It wasn't just the Jews that were boiling up blue dye. Pliny the Elder (23-79 CE.) lived at least two  centuries before Abaye and Rav Shmuel, and left us his own version of the process outlined in today's page of Talmud:

The most favourable season for taking these fish is after the rising of the Dog-star, or else before spring... After it is taken, the vein is extracted...to which it is requisite to add salt, a sextarius [~20oz] to every hundred pounds of juice...leave them to steep for a period of three days...then set to boil in vessels of tin... About the tenth day, generally, the whole contents of the cauldron are in a liquified state, upon which a fleece...is plunged into it by way of making trial...The wool is left to lie in soak for five hours, and then, after carding it, it is thrown in again, until it has fully imbibed the colour... To produce the Tyrian hue the wool is soaked in the juice of the pelagiæ while the mixture is in an uncooked and raw state; after which its tint is changed by being dipped in the juice of the buccinum [a sea snail]. It is considered of the best quality when it has exactly the colour of clotted blood, and is of a blackish hue to the sight, but of a shining appearance when held up to the light; hence it is that we find Homer speaking of "purple blood".

So Pliny described a “fish” as the source of the dye. Was this the sea creature called the chilazon? Later in this tractate, (44a) we have another description of the mysterious chilazon.

ת"ר חלזון זהו גופו דומה לים וברייתו דומה לדג ועולה אחד לשבעים שנה ובדמו צובעין תכלת לפיכך דמיו יקרים

The Sages taught: This chilazon, [which is the source of the sky-blue dye used in ritual fringes, has the following characteristics:] Its body resembles the sea, its form resembles that of a fish, it emerges once in seventy years, and with its blood one dyes wool sky-blue for ritual fringes. It is scarce, and therefore it is expensive.

It is sea-like and fish-like and is rare ("once in seventy years"), and it is hard to find. OK, but not terribly helpful in figuring out its identity.

As early as 2,000 BCE the Phoenicians had been producing a blue-purple dye from shellfish. The identity of this chilazon creature was clear to the Romans and to sages of the Talmud, but it was lost over the centuries. Or almost lost. It was a point of scholarly and religious debate in the nineteenth and twentieth centuries, and then some neighbors of mine when I lived in Eftat figured it out. 

“As early as 2,000BCE purple dye was associated with the Phoenicians, who traded in purple-dyed fabrics...The word “Canaan” may derive from the Akkadian kinahhu, “red-purple,” while “phoenicia” probably comes from the Greek phoinos, “dark-red”...the shellfish utilized for these dyes are the Murex trunculus and the Murex brandaris. The shellfish were crushed, boiled in salt, and placed in the sun; afterwards the secretions turned purple. Eight thousand mollusks yielded one gram of purple dye.”

— Philip King & Lawrence Stager. Life in Biblical Israel. Wstminster John Knox Press 2001. 161

Identifying the Chilazon

1. The Rebbe of Radzyn

The tradition of using a sea creature to dye clothing was never entirely lost. In 1685, for example, a Mr William Cole of Bristol reported that a "purple-fish" (by which he meant a sea snail or mollusk) was being used to dye "fine linens of ladies and gentlemen" on the coast of Ireland. But it wasn't until the nineteenth century that the search was taken seriously by the Jewish community.

“...there was a certain person living by the Sea-side in some Port or Creek in Ireland, who made considerable gain by marking with a delicate durable Crimson Color, fine Linnen of Ladies, Gent &c...made by some liquid substance taken out of a Shell-fish...”

— A Letter from Mr William Cole of Bristol, to the Phil. Society of Oxford; Containing His Observations on the Purple Fish. Philosophical Transactions 1685. 15;1278-1286

The common cuttlefish - the source of the Radzyn techelet. Courtesy of the Monterey Bay Aquarium.

It was R. Gershon Henoch Leiner, the Rebbe of Radzyn(1839-1890) who began the modern search for the clilazon. Once the creature had been identified he argued, it would be used dye the strings of the otherwise white tzitzit, and return to a more authentic observance of the mitzvah. The search brought the rebbe to Naples, Italy, where he concluded that the cuttlefish (sepia officinalis), a kind of squid, was the long-lost chilazon. The cuttlefish produced a dark ink when threatened, and after some help from local chemists, he hit on a method to turn that ink into a blue dye. 

However, there were three problems with the Radzyn techelet. First, Maimonides in his Mishnah Torah ruled that techelet must resist fading, but the Radzyn dye could be easily washed out.

“וְהַתְּכֵלֶת הָאֲמוּרָה בַּצִּיצִית צָרִיךְ שֶׁתִּהְיֶה צְבִיעָתָהּ צְבִיעָה יְדוּעָה שֶׁעוֹמֶדֶת בְּיָפְיָהּ וְלֹא תִּשְׁתַּנֶּה
The blue thread mentioned in connection with fringes must be dyed with a special dye which retains its color and does not change...”

— Maimonides. Laws of Tzitzit 2:1

Second, in order to produce Radzyn techelet, the cuttlefish needed to be killed to extract its ink.  But the Talmud (Shabbat 75a) notes that the longer the chilazon is alive, the better its dye (דכמה דאית ביה נשמה טפי ניחא ליה כי היכי דליציל ציבעיה).  And the third problem with the Radzyn-cuttlefish-is-techelt theory was Rabbi Isaac Halevi Herzog.

2. Rabbi Isaac Halevi Herzog

The Banded Dye-Murex, Murex trunculus. From here.

Rabbi Isaac Halevi Herzog (1888-1959) was born in Poland and at the age of ten emigrated with his family to Leeds in the north of England. There he was educated in talmudic studies mostly by his father, and he later attended the University of London There, the topic of his PhD thesis was "The Dying of Purple in Ancient Israel" and focused on the identity of the chilazon. R. Herzog went on to succeeded Rabbi Abraham Isaac Kook as the Ashkenazi Chief Rabbi of Palestine, a position he held from 1936-1948.

R. Herzog was critical of the conclusion of the Rebbe of Radzyn that identified the common cuttlefish as the chilazon.  In 1909 he had the Radzyn dye sent to the accomplished German chemist Paul Friedlander, who had earlier identified (or re-identified) the murex trunculus as the source of the dye called Tyrian purple (a discovery for which Friedlander was awarded the Lieben Prize in Chemistry). Friedlander tested the Radzyn dye and concluded it was itself unable to produce the blue color of techelet. Others chemists concluded that the Radzyn dye was in fact a synthetic compound known as Prussian blue, produced by the oxidation of ferrous ferrocyanide salts. This was confirmed when R. Herzog obtained the recipe for the dye from Radzyn hasidim. It called for the cuttlefish dye to be heated with iron filings and potash, and these hasidic dyers were actually making Prussian blue.  In fact the color of the Radzyn dye was nothing to do with the cuttlefish - it all came from the added chemicals. This left R. Herzog with a problem: if the cuttlefish was not in fact the chilazon, well then what was?   

Although it was known that the murex could produce a purple-blue dye, R. Herzog rejected this for the following reasons:

1. The snail does not appear "once every seventy years" yet this description appears in the Talmud (on 44a).  

2. The dye is not color fast. Or at least that is what he thought.  

3. The dye is a purple-blue color. But techelet is sky blue, as the great Rabbi Meir reminds us:

סוטה יז, א

היה ר"מ אומר מה נשתנה תכלת מכל מיני צבעונין מפני שהתכלת דומה לים וים דומה לרקיע ורקיע דומה לכסא הכבוד

R. Meir used to explain how techelt is different from all other colors: The color of techelet is similar to the color of the ocean; and the color of the ocean is similar to the color of the sky; and the color of the sky is similar to God's Glorious Throne.

Poor Rabbi Herzog never did reach a conclusion about the identity of the chilazon. But he was certain of two things. The Radzyn dye was not techelet, and the Radzyn cuttlefish was not the chilazon. Something was missing. And that something was sunlight.

It is all about the sunlight. From Ptil Tekhelet.

The dye produced from the murex snails is indeed dark purple and not permanent, but (and this is super important) if it was exposed to bright sunshine it turned a magnificent sky-blue color, and it didn't fade or wash out.  This was discovered quite by accident in the early 1980s by Dr. Otto Elsner of the Shenkar Institute in Tel Aviv. Chemists who had produced the purple dye from the murex snail had done so in their labs, far away from natural sunshine.  But the dye extracted from the gland of the murex snail, when exposed to sunlight, turns blue in color. Bingo. Sky-blue techelet. 

“Elsner researched the chemical process taking place in his sun-drenched dye mixture and discovered that while in solution the dye molecules are less stable than in their natural condition. Ultraviolet energy - such as found in the rays of bright sunlight - can break the bonds that attach some of the atoms to each other within the dye molecule. These photochemical processes alter the purple and red constituents of the murex extract and leave primarily indigo, which is of course, pure sky blue.”

— Baruch Sterman and Judy Taubes Sterman. The Rarest Blue. Efrat, Ptil Techelet 2012. 127.

3. my neighbors in efrat.

In the late 1990s I lived in Efrat, part of the Gush Etzion Block, and was a neighbor of Baruch and Judy Sterman.  It was their hard work, together with Ari Greenspan, Joel Guberman, and many others, who helped restore the ancient tradition of techelet. While the ability of the murex to produce the dye was already known, and the need for ultraviolet light to fix the dye had been fortuitously discovered, this group perfected the harvesting of the snails, (which involved, I kid you not, Greek and later Croatian fishermen) and set about manufacturing techelt-dyed tzitzit on a large scale. To date their organization Ptil Tekhelet have produced some 200,000 pairs, as well as this excellent guide to the process for those who are learning this passage in the Daf Yomi cycle. For a deep dive into all things techelet, I also recommend their fascinating book “The Rarest Blue.”

The ABSORPTION Spectrum of Murex Techelet

In 1991, Wouters and Verhecken published High-performance liquid chromatography of blue and purple indigoid natural dyes in the rather niche Journal of the Society of Dyers and Colourists. The two Belgium chemists measured the absorption spectra of various indigo containing dyes including “silk fabric, stained with the contents of the hypobranchial gland of Murex trunculus.” The absorption spectrum measures the wavelength of radiation (or light) absorbed by an object, and it is this absorption that gives objects their color. Here is the absorption spectrum of indigotin, the color-giving component of techelet:

Absorption spectrum in the u.v. and visible light region of Indigotin. From JWouters and A Verhecken. High-performance liquid chromatography of blue and purple indigoid natural dyes. JSDC 1991: 107; 266-269.

As you can see there is a peak around 613nm. A similar finding was reported in 2015 by a researchers from the Israel Antiquities Authority and Bar-Ilan University, when they examined textiles found in a cave in Wadi Murabba'at, the Judean desert. The textiles date to the Roman period, were identified as having been dyed with using the murex sea snail Hexaplex trunculus. Here is the absorption spectrum they published:

UV–visible spectra of the compounds found in Murex species: indigotin (IND) and its derivatives, monobromoindigotin (MBI) and dibromoindigotin (DBI), with absorbance maxima between 601 nm and 613 nm; indirubin (INR), monobromoindirubin (MBIR), and dibromoindirubin (DBIR) with absorbance maxima between 536 nm and 544 nm. From Sukenik et al. Chemical analysis of Murex-dyed textiles from wadi Murabba'at, Israel. Journal of Archaeological Science: Reports. 2015; 3:565–570.

It too reports that indigotin (and its derivatives) have absorbance maxima between 601nm and 613 nm.” The number 613 of course has a special significance in Judaism; it is the traditional number of commandments that Jews must observe. This coincidence was noted by the Ptil Tekhelet organization who note it in their guide to Menachot chapter 4:

Now in fact, as you can tell from the figures above, the peak absorption spectrum of indigotin is not 613nm, but in the 200-300nm range. However this peak lies in the ultraviolet part of the spectrum, and so is not visible to us (though bees are able to see it). Make of this finding what you will.

A do-it-yourself guide to making techelet

This week I carried out a very unscientific survey of the number of techelt colored tzitizit worn in my shul. Out of a total of 58 talesim, 7 (12%) had techelet fringes (and I saw no techelet fringes in the women’s section). So if you want to get a set for yourself, you can either buy a ready-made pair, or do-it-yourself and follow this recipe (courtesy of Baruach Sterman).

1. Find the snails, break them open and extract the glands

2. Mush those glands in a food processor (they take on a dark purple hue), and then dry them out (at this point they are very stable and can be stored for a long time - even years - without refrigeration).

3. When ready to dye, put the dye into solution and produce a chemical process called reduction. To do that add water and a base and a reducing agent (Baruch uses sodium dithionite) and heat moderately. (In ancient times this was done by a two-week fermentation process which has been replicated).

4. Once the dye is in solution it takes on a green-yellow color (this is called leuco-indigo) and at that point expose to sunlight. Then immerse the wool/threads.
   

5. When the wool is removed and exposed to air, the dye undergoes oxidation and takes on its final color - and becomes insoluble again which keeps it fixed in the wool matrix.

That’s all there is to it. So what are you waiting for?