It was only very recently that the convergence of renewed study of the relevant Torah sources chance archaeological finds and serendipitous discoveries in marine biology and dye chemistry has led many to the conclusion that the source of the ancient techeiles was the Mediterranean sea-snail Murex trunculus. Although most Jews continue to wear the traditional tzitzis with white strings there is a greater interest today in techeiles strings in many Jewish communities.

But this growth in demand and production has left us with a sense of concern and a feeling of deep responsibility. We at Ptil Tekhelet want to ensure that techeiles will be affordable and available to every Jew who chooses to wear it now and for future generations. It was this sentiment that brought me to Huatulco in Mexico.

The Gemara contains many interesting descriptions and statements regarding the chilazon including how and where it is caught and how the dyeing process was carried out. The writings of contemporary Greek and Roman naturalists augment the Talmudic accounts. Like today in ancient times the snails were caught in baited nets and the dye was extracted by breaking open the shells and removing a tiny gland covered with mucus — what the Gemara calls dam chilazon the blood or secretion of the snail. This must be done while the snail is still alive because as the Gemara states (Shabbos 75a) the dyer “prefers that it should be alive so that the dye should be clearer.”

The chilazon was found throughout the Mediterranean “from the cliffs of Tyre to Haifa” (along the northern coast of Israel and into Lebanon) and as far as the Isles of Elisha (probably Cyprus Crete Greece or Italy).

Over the years we have obtained our snails from a number of places. At one point we were importing them from southern Spain but then an oil spill off the coast of Gibraltar led to a complete ban on fishing in that region thus shutting off our supply for nearly two years. This event taught us caution as well as the importance of stockpiling reserves of dye to ensure uninterrupted production of techeiles regardless of man-made or natural disasters. Though our supply of snails is currently abundant and stable we are constantly looking for additional sources.

That is why I was intrigued when I received an e-mail from Kathy a school teacher in Chicago who had read my book The Rarest Blue which tells the story of the loss and rediscovery of techeiles. Kathy traced her family roots back 500 years to Marranos who fled Spain and the Inquisition to the promise of safety in the New World. They settled in the hills of Oaxaca Mexico in the small town of Pinotepa de Don Luis which happened to be home to a large population of Mixtec Indians an indigenous people who had been living in that region for thousands of years.

One of the most noteworthy features of Mixtec culture is their use of sea snails to dye beautiful purple fabrics for commercial as well as ritual purposes. Kathy’s family still lived in Oaxaca and she asked if I would be interested in joining her on her next visit to meet the Mixtec dyers and to learn about their methods.

Beyond my sense of adventure, and curiosity about an exotic culture and a fascinating history, and even apart from the practical and ongoing search for alternative supplies of techeiles dye, the trip held a special fascination for me. I was aware that over the centuries the Mixtec dyers had perfected a unique method of “milking” their snails, and could obtain dye from the same snail multiple times, sparing them so that they could live — and dye — another day. Might this be a technique that we could potentially employ in our techeiles dyeing? I replied to Kathy that, of course, I would be excited to visit the Mixtec.

In preparation for the trip, I consulted with several rabbanim regarding the halachic issues involved in the possible use of the Mixtec snails, Plicopurpura pansa, as a source for techeiles. After all, it was clear that Chazal never had access to the Mexican mollusks, which are found only in the Pacific Ocean and were certainly not used for making techeiles in Biblical or Talmudic times.

Some rabbanim with whom we consulted were doubtful that any snail other than the authentic Mediterranean Murex could be a valid chilazon. They were further skeptical about the Mexican snail and its unique method of dye expression. They quoted the Gemara in Shabbos (75a) that discusses killing the snail — “Hatzad chilazon v’hapotzo — One who traps the snail and breaks it open” — which would indicate that this method of obtaining the dye as opposed to the Mexican “milking” is an integral part of the process from a halachic standpoint. Moreover, that process might describe an identifying feature of a particular snail that alone could be used for techeiles.

Another posek with whom I consulted looked at the snail question a bit differently. He responded that the main halachic constraint regarding the source of kosher techeiles is “techeiles ein keshera ela min hachilazon — only techeiles obtained from a chilazon is acceptable.” Was the Mexican snail a chilazon? “The definition of a chilazon is a sea creature with a hard shell,” he answered, “so I would tend to think that [the Mexican snail] is permissible to use for techeiles.”

I was encouraged by that approach, which warranted, at the very least, a more thorough exploration of the topic to bring a more complete set of facts back for rabbanim for their consideration.

Blue Like the Sky

Traveling from Israel to Oaxaca (a long and exhausting journey that took me more than two full days and three canceled flights) reminded me of another trek taken in the service of techeiles, almost 130 years ago. In 1889, Rav Gershon Henoch Leiner, the Radziner Rebbe, left his chassidim behind and traveled from his home on the border of Poland and Russia across the continent to the southern tip of Italy and the city of Naples. There, in the newly opened aquarium — the very first of its kind — the Rebbe searched for a creature that might fit the descriptions of the techeiles chilazon. After a year he returned to Radzin triumphant, having determined that the cuttlefish Sepia officinalis, was the authentic chilazon, and he had procured a recipe for turning its brown ink into a deep blue dye. Though thousands of his chassidim were soon wearing techeiles on their tzitzis, the Rebbe’s innovation never really caught on beyond his community.

Various objections were raised to identifying the cuttlefish as the chilazon, but the most compelling challenge was delivered nearly a quarter century later by Rav Yitzchak Isaac HaLevi Herzog. Still a young man in 1914 (later he would become chief rabbi of Ireland, then the first chief rabbi of the State of Israel), Rav Herzog wrote a doctoral dissertation on “Hebrew Porphyrololgy” (a word he coined to mean the study of purple). He examined the topic of techeiles from every possible angle, and as part of his research, Rav Herzog had strings of Radzin techeiles examined by laboratories across Europe. Based on their findings, along with correspondence with the dyers of Radzin (Rav Gershon Henoch himself died in 1891), Rav Herzog determined that the blue color of the Radzin techeiles came not from the sea creature itself, but rather from the chemicals added as part of the dye process. Therefore, he felt that this could not be authentic techeiles.

Already at that time, Rav Herzog believed that the Murex trunculus snail was the most likely candidate for the chilazon. He hesitated to make that determination conclusively, however, for a number of reasons, the most crucial of which was that the Murex snail produced a purple dye. Techeiles, Rav Herzog emphatically asserted, must be blue like the sky, so that when we look upon the thread — “u’re’isem oso” — our thoughts are raised to the heavens, to Hashem, and to His mitzvos.

The resolution to this problem would not come in Rav Herzog’s lifetime. It was only in 1985, close to 25 years after his death, that researchers in Israel discovered that at a particular stage in the dyeing process, exposure to sunlight could turn the Murex dye from purple to a beautiful shade of pure sky-blue.

On the plane to Mexico, I felt a deep appreciation for the Radziner’s work. He had laid the groundwork for the rediscovery of techeiles, had written three books discussing all aspects of the halachos involved, and opened the hearts and minds of Jews to the importance of this mitzvah and to the possibility of its being fulfilled once again. Both he and Rav Herzog had become my role models, mentors, and inspiration.

Smell of the Snails

At the Oaxaca airport, I was greeted by Kathy and Dr. Marta Turok, an anthropologist with the Mexican government who had spent decades researching the Mixtec peoples. They had prepared a packed agenda for the week, but the most important part for all concerned was working with the dyers and the snails, and trying to determine if the purple dye they produced could indeed be used to make techeiles.

We got to work almost immediately, going directly to one of the beaches in Huatulco, where I met the rest of the team. Delia was a marine biologist at the University of Nayarit, Mexico, who had spent many years researching the Plicopurpura, their life cycle, anatomy, and environment. And, of course, Habacuc, the Mixtec dyer — the oldest and most experienced of the nine remaining traditional dyers still practicing the ancient craft.

The first day we took a trip to the rocky shore to view the snails themselves and to experience firsthand the dye secretion. The Plicopurpura adhere to rocks just above the waves, and when you pull them off — and it does help to spit on them — a yellow liquid starts to collect inside the shell aperture. I let it ooze out onto my hands and watched as over a few minutes the yellow turned purple. This was not surprising to me. The dye from our Mediterranean Murex snails undergoes the same transformation as we break them open and extract the gland that is covered with a similar yellow paste.

As I expected, the purple stained my fingers, and I knew it would take a few weeks to fade. I smelled my hands and recognized the familiar pungent garlic-like odor. Habacuc watched what I did, and I mentioned (with Delia translating) that our snails back in Israel had the same smell. He was excited to hear that and told me that when he comes home from dyeing, his family complains about the smell. I exclaimed that my family feels the same way, and we both laughed. It was an interesting moment: two men from opposite sides of the world, from cultures and backgrounds poles apart, with no common language, yet connected in some deep way through their shared appreciation for the wonders of the magnificent dye-producing snails — he for his reasons and I for mine.

My first encounter with the Plicopurpura encouraged me, since the characteristics of its secretion were comparable to those of the yellow substance we obtained from our snails. The real test would be to see if that secretion behaved similar to the Murex during exposure to sunlight and if it indeed could be transformed into techeiles.

That night we learned more about the Mixtec and their purple dyeing. Traditionally, only men may do the dyeing, and it is forbidden for women to touch the snail, called T’shiinda Ya-A in Mixtec. In old times, the dyers, Ra Yaki Yuba-A — literally, the men who dye threads — would come down from Pinotepa de Don Luis in the mountains to the coast of Huatulco, a trek that took up to 12 days on foot, laden with as much cotton yarn as they could carry. They would spend weeks dyeing all those threads, and working in the local fields in return for food and shelter.

After three months or so, when all the cotton was finally dyed, they would return to the village, where the women would weave the purple threads into scarves, shirts, and especially skirts. The most beautiful and meaningful of the skirts was called a Che-Eh, and it was worn by a bride at her wedding, after which it was set aside, never to be used again until her death, when she would be buried in it.

I was struck by the symbolism of the purple color, which the Mixtec associated with blood — the blood of childbirth, fertility, and death.

In the ancient Mediterranean and Near Eastern cultures, the association of purple and blood came to represent the victorious hero in battle. The most prestigious of all Roman dress was the toga picta, all purple and hemmed in gold, worn only by a triumphant general returning from war. The connection of purple (argaman) and blood is noted by the Ramban as well, who explains that in the Mishkan, the Mizbeiach was covered with a purple cloth because the blood of the karbanos was sprinkled on it.

Though purple was prized above all other colors, both by the Mixtec and the ancient cultures around Israel, the Jews esteemed the sky-blue techeiles as the most valuable and holiest of all colored fabrics. Purple, though beautiful, is earthy, but techeiles soars above and reaches to infinity. The Gemara in Sotah (17a) states: “Rabi Meir would say: ‘Why is techeiles singled out from all the colors? Because techeiles is similar to the sea, and the sea is similar to the sky, and the sky is similar to [Hashem’s] Holy Throne.’ ”

Breaking the Bromine Bonds The following day we set out early by boat under Habacuc’s direction to a secluded cove that held a very large number of Plicopurpura. Our anthropologist explained that the Mixtec, who have been dyeing for centuries, adhere to four principles that have helped keep the snail population healthy and strong. First, they do not touch snails that are mating, so as not to interrupt the reproductive process. Second, they do not use juvenile snails. Third, they do not come back to the same cove until at least one month has passed. And last, they take care not to harm the snails and to gently return them to the rocks after “milking.”

I followed Habacuc over the slippery rocks in search of the snails. He would take each snail and lightly press it against the cotton threads, which absorbed the yellow liquid. As the day progressed, the skein of yarn changed colors from shades of yellow to green and eventually, to its final purple. I was busy meanwhile collecting the liquid from each snail in a bottle, one by one, drop by drop. Habacuc and I worked together for close to six hours under the hot equatorial sun.

After milking close to a hundred snails, I had about a quarter-cup of liquid, which had turned a rich dark purple. Habacuc was annoyed with me, since as far as he knew, once the snail discharge turned purple, it would no longer adhere to the threads. In other words, he felt that I had wasted all that dye. But I knew that the ancient Mediterranean dyers who broke open their snails and collected the glands had learned to take that purple and process it, so that it could adhere to a fabric and be used for dyeing.

The Gemara tells how the great Amora Abaye, who lived in Bavel far from the techeiles factories of Eretz Yisrael, asked Rav Shmuel bar Rav Yehuda: “Ha tachilta, hechi tzaviso la? — This techeiles, how do you dye it?” Rav Shmuel, who lived in Eretz Yisrael, explained how the dyers took the “blood” (secretion) of the chilazon, added chemicals, and boiled the mixture in a vat. And that was precisely what I intended to do with the liquid in my bottle.

Back in Huatulco, I set to work on the final and crucial part of my experiment, and I was nervous and unsure if it would succeed. Were these Mexican snails really similar to their Mediterranean counterparts, and would the dye obtained from them have identical properties and characteristics? My conditions were far from laboratory grade, as the dyeing would take place outside, over a chafing dish burner that we got from a nearby restaurant, and I would be mixing in chemicals with no accurate way of measuring the amounts or knowing the concentration of the dye within my liquid. It was also late in the day, and I was worried that the sunlight might not be strong enough to effect the changes from purple to blue.

In terms of chemistry, I was going to put the dye into a condition known as reduction to dissolve it in water, allowing the wool to soak it up. In that state, the ultraviolet rays of the sun would break the bromine bonds, after which, removing the wool from the water and into the air (oxidation) would lock the molecules firmly within the wool fibers. In practical terms, I would be turning the purple liquid a dark yellow-green, exposing it to sunlight, and immersing the wool. If everything went as planned, when I removed the wool it would change from yellow to blue.

The entire process took about 45 minutes, and with our entire team looking on, I finally extracted the tuft of wool and waited. Slowly, magically, the color began to transform. First bright yellow, then green, then gray, and finally, a majestic, gorgeous blue — so similar to the Pacific Ocean behind me and the tropical sky above. For the first time in history, techeiles had been obtained from a snail outside the Mediterranean, and without a single creature being harmed.

Beyond the Edge

The remainder of the trip was wonderfully exciting, informative, and educational, and an opportunity to forge a connection with exceptional people and far-off places. One incident stands out in my memory and made a deep impression. Habacuc had not been particularly moved by the fact that we could obtain blue dye from his snails and felt that it was just some kind of chemistry trick. One evening I was explaining the meaning and importance of techeiles in the Jewish tradition, and took out my tallis. I showed the tzitzis — white and techeiles — and the intricate tying method (tying tzitzis with techeiles is very different from tying all-white tzitzis). I unfolded my tallis and showed him how every morning I wrapped it over my head and around my body and quoted the pasuk, “U’vnei adam b’tzel kenafecha yechesayun — that all men take refuge in the shadow of Your (Hashem’s) wings.” Coming out from under my tallis I glanced at Habacuc and saw that he had a tear in his eye. I thought of how beautiful the mitzvah of tzitzis really is, something taken for granted and lost in the routine of daily habit.

It reminded me of an idea that the Radziner Rebbe suggested to explain why we wear tzitzis specifically on the edge of the garment. A person’s clothes represent his character, his station, the image he wants to portray to the world. “Clothes make the man,” and to a certain extent define him. But that self-definition can also be constraining, because it limits you to what you are now, to your daily structure, and what you believe to be the extent of your capabilities. It confines you to your perceived limitations and self-imposed boundaries. But the techeiles and white strings of the tzitzis break through those boundaries; they hang from the corner of your garment and extend beyond the edge, full of potential and off into infinity. The garment symbolizes what you are, the tzitzis symbolize everything you could be.

Back in Israel I met with my friends, the cofounders of Ptil Tekhelet, to debrief and discuss the trip. We recognized that there was much more work and research necessary before any practical applications could be considered, not only in terms of logistics and technical issues, but even more so in the realm of halachah. We would need to consult with rabbanim to probe their views, and we realized that in all probability we would never use the Plicopurpura snails instead of the authentic Murex trunculus to make techeiles.

But there is, nonetheless, a very important lesson to learn from the encounter with the Mexican dyers. They have a deep respect for the welfare of their snails, and do all they can to protect that valuable resource upon which they so profoundly depend. We must do no less with our precious resources.

This is part of our solemn and crucial undertaking, of our charge to be shomrei mitzvas techeiles. The pasuk in Shema says, “V’asu lahem tzitzis al kanfei bigdeihem l’dorosam — And they shall make for themselves tzitzis on the corners of their garments throughout their generations.” It is our responsibility to safeguard and protect the chilazon in order to ensure that techeiles remains available and affordable l’dorosam — for all future generations.

The Techeiles Debate- Is the murex really the Biblical source of the mysterious blue dye?

The Evidence Is All There

Rabbi Zevulun Kormim

We all know that the mitzvah of tzitzis is comprised of white and techeiles strings. If techeiles is available and one neglects wearing it, he has neglected a mitzvah d’Oraisa. But is the Murex trunculus snail the correct source of techeiles?

One brief introduction: Rav Chaim Kanievsky related to Rav Moshe Mordechai Karp (the noted posek of Kiryat Sefer) that anyone choosing to wear techeiles may do so publicly; and in a video on techeiles.org, Rav Chaim can be seen saying that anyone convinced of the authenticity of the Murex is obligated to wear it. Indeed, though Murex-based techeiles has not gained widespread support, many noted poskim and roshei yeshivah do wear techeiles. What are the considerations that move these Rabbonim to use the Murex techeiles?

Chazal state that the source of the techeiles is a chilazon, that it must be blue, and that it must remain strong and not fade. Murex meets these criteria as detailed below:

The term chilazon means a snail as the Pesikta (B’Shalach 11) states “a chilazon’s narteik (shell) grows with it.” Rambam identifies a certain metal ring as “a shell made of iron, like the shell of the sea creature called chalazun.”

Rabbeinu Gershon and Rashi define a chilazon as a “limatz” in old French. Rashi (Chagigah 11a) writes that a limatz is a “sheretz that grows with a shell which continues to grow around and around” — i.e., a snail. The Aramaic word chilazon is identical to the word for snail in Middle Eastern languages such as Farsi, Arabic, and Syriac.

A number of early and late Acharonim translate chilazon as purpura, which is a general type of snail, of which Murex trunculus is a subspecies. Reb Avraham Harofei (Shiltei Hagiborim Perek 79), Chavos Yair (Mekor Chaim 18:3), Tosafos Re’em (Al Sefer Yereim 401:17), Rav Hirsch (Devarim 33:19).

Chazal (Menachos 42b) tell us that false techeiles is produced from “kala ilan” — i.e., plant indigo (as per Aruch), an ancient blue dye. The blue dye produced by indigo (kala ilan) is virtually identical to the dye produced by the Murex.

The Gemara (ibid.) writes that kala ilan will fade after a complicated chemical procedure is applied to the material whereas true techeiles will not fade from the material. In fact, the Murex snail is known from antiquity as famously color-fast and enduring.

It is clear from the aforementioned Gemara in Menachos that these (plant-based indigo and the Murex) were the only two items known to Chazal that produce this dye. Murex dye existed in the days of Chazal as found in ancient dye pits in the precise locations mentioned by Chazal (Shabbos 26a). Since both Murex and indigo produce blue dye, it must be that Murex was the chilazon that Chazal used.

Numerous sources in Chazal tell us that techeiles was used by royalty. It is well established through historical records that the Romans wished that that techeiles be used by royalty exclusively, and therefore banned the use of Murex dye by all others.

The timeline of the Roman decrees restricting techeiles correspond precisely with the Gemara’s description of the techeiles restriction. Indeed, it is for this very reason that it was “nignaz”or “stored away.”

Many Rishonim and Acharonim report that techeiles can return at any time (Maharil, Chadashos 5). In fact, the Levush (intro to Orach Chayim) writes that if techeiles is found we are obligated to wear it. These commentators obviously understood that nignaz means simply that techeiles was hidden; it does not specify for how long and under what conditions.

The Gemara (Shabbos 75a) says the dye is more effective if it is taken from the chilazon while it is still alive. Murex dye is removed immediately after the snail dies, because the quality decreases the longer the snail has been dead.

Chazal state that techeiles dying was widespread on the Mediterranean coast from Haifa to Tyre, in the very place where huge mounds of Murex snail shells have been found with their shells cracked where the dye pouch is extracted.

The blue color of the Radziner techeiles was demonstrated to be produced by an additive, which is obviously not the case with the Murex. Nor did that techeiles conform with the many proofs detailed above.

There are numerous other sources demonstrating that the Murex is in fact the chilazon. Readers are invited to visit techeiles.org and the numerous (both pro and con) resources cited there to investigate further. Particularly succinct is Sefer Levush Aron (downloadable there, both in Engish and Hebrew) that details the proofs and addresses the objections raised against this identification.

Reason to Doubt

Rabbi Yirmiyohu Kaganoff

Why do the vast majority of rabbinic authorities reject the Murex trunculus snail as the source of techeiles? After all, since one must be stringent regarding doubts of Torah law (safeik d’Oraisa l’chumra), perhaps techeiles should be worn out of doubt, due to the mere possibility that it is the true chilazon.

Without discussing whether safeik d’Oraisa l’chumra applies to positive mitzvos, the Radziner Rebbe, “the father of modern techeiles” rules in one of his many works that one who is uncertain whether an item is techeiles should indeed wear it on his garment. In his opinion — and there is strong halachic merit to this position — nothing is lost by wearing a dye on tzitzis, even if it is not kosher techeiles.

If one asks Rav Chaim Kanievsky whether one should wear Murex-dyed tzitzis, he will answer simply: The Midrash records that the chilazon was “hidden”— and he, as well as many others, take the Midrash literally. Hence, any species to which we have access today cannot be the correct chilazon. Obviously then, neither the cuttlefish (a variety of squid) that the Radziner identified with the chilazon, nor a sea snail that Rav Yitzchak Isaac HaLevi Herzog identified as chilazon, can be the source. Rav Chaim has told people “it makes as much sense to wear this dye on your tzitzis as it does to put a cat on them.”

Obviously, neither the Radziner Rebbe nor Rav Herzog felt that we must interpret the Midrash this way. Yet the consensus of those who disputed the Radziner did. In addition, the Beis HaLevi, Rav Yosef Ber Soloveitchik, objected to the Radziner’s techeiles based on mesorah. According to the version quoted by the Radziner himself, the Beis Halevi held that since the cuttlefish is a known species, and since for over a thousand years it was not used to dye tzitzis, it cannot possibly be the chilazon. Such a mesorah would never have been lost.

Rav Joseph Ber Soloveichek, the late rosh yeshivah at Yeshivas Rabbeinu Yitzchak Elchanan (RIETS), interpreted his great-grandfather’s position differently, namely that a mitzvah object cannot be identified on the basis of logic, but only on the basis of mesorah. Therefore, all the proofs in the world cannot demonstrate that a given species is the true chilazon.

However, aside from the Midrash and the need for a mesorah, there are many other reasons to reject the cuttlefish or any marine snail as the chilazon. When the Radziner published his research, he communicated directly with the greatest halachic authorities of his generation, virtually all of whom disagreed with him. None accepted his approach, even to consider it a safeik. (The one exception was the Maharsham, who, on the possibility that the Radziner might be correct, reputedly wore a tallis katan with Radziner techeiles, although he made sure that no one ever saw him do so.) The reasons these poskim rejected the Radziner’s cuttlefish apply equally to the Murex trunculus.

It is true that Rav Herzog rejected the cuttlefish as a source of the techeiles because the coloring agent used in the Radziner’s techeiles was a synthetic dye created by chemicals unrelated to the cuttlefish. However, a careful read of the Radziner’s writings will demonstrate that this factor would not have changed his mind, and that the rabbanim who objected to the Radziner’s techeiles did so for reasons that apply equally to Murex trunculus–based dye. Among those reasons are the opinions of Rishonim that the chilazon of techeiles must be a kosher species, and neither the cuttlefish nor the sea snail qualify.

In addition, there is a very strong argument running against any sea snail as the source for techeiles. Notwithstanding the contentions of Murex advocates, the depiction in the Gemara of the chilazon as a fish does not fit a snail. And the Rambam’s description of the black dye produced by the chilazon does not fit Murex trunculus. These arguments were not raised against the Radziner’s cuttlefish since it does fit the description of the Gemara and the Rishonim.

When Rav Elyashiv was asked about wearing Murex dye because of the safeik, he answered, very enigmatically: one should not wear it, because when the true techeiles becomes available, those who invested in the Murex will find reasons to reject the true chilazon techeiles.

We should note several factors: In his doctoral dissertation, Rav Herzog concluded that none of the sea snails he had investigated were the proper sources for techeiles, although he was convinced that the chilazon was a sea snail. He believed this in part because the word chilazon means sea snail in other Semitic languages. He also knew that in many ancient societies, dyes were made from sea snail extractions, and that there were sources in Greek literature that discuss creating dyes from snails. I note that none of these factors are halachic.

Rav Herzog also notes that his opinion about the chilazon runs counter to Rashi and other Rishonim. The key passage here is a gemara in Shabbos (75a) (“Hatzad chilazon v’hapotzo — One who traps the snail and breaks it open”) in which Rashi explains that the word “potzeia” means to squeeze. But the Murex dye is not acquired by squeezing. Rav Herzog, who assumed that chilazon was a snail, explains potzeia means to smash, though he concedes that his understanding differs from that of Rashi. Since our halachic knowledge and interpretation in virtually all areas is based on our mesorah from the Rishonim and how they understood critical passages of the Gemara, Rashi’s approach is halachically authoritative.

By the way, in Rav Herzog’s dissertation, he ultimately rejected all of the sea snails he researched, including Murex trunculus, as the source of techeiles because they could not produce a light blue dye — and he was convinced, based on Jewish mesorah, that techeiles is a light blue color. It is true that, since his passing, a method has been discovered whereby one can create a purplish-blue from Murex trunculus, but this color is not the sky blue that Rav Herzog thought was the true color of techeiles.

There is one strong argument to support the use of Murex trunculus as the source for techeiles: It is indeed unusual to find sea creatures from which one can obtain a blue dye. However, a lack of knowledge about other marine-based blue dyes does not wash (pun intended) as a halachic argument.

For those who point to archaeological evidence that sea snails were used in Eretz Yisrael for dyeing, I share the following thought: Perhaps the sea snails found were used for dyeing argaman, and perhaps the purplish color that one gets from Murex is indeed argaman and not techeiles? Perhaps the true color of techeiles is indeed sky blue, as Rav Herzog insisted, and there is a kosher marine creature that Hashem indeed hid that has a black extract, as the Rambam states, and produces a techeiles-colored dye when squeezed, as Rashi states?

If someone is convinced that Murex is the correct source of techeiles, should he wear this dye on his tzitzis? Although both Rav Chaim Kanievsky and Rav Asher Weiss contend that one has absolutely no obligation to wear techeiles that comes from Murex, there is reason to believe that both rabbanim have advised those who believe Murex is the true source of techeiles to wear it on their garments. I would assume that this would be dependent on their understanding of the halachic rule shavyei anafshei (subjective establishment of prohibitions) although I would not want to speak for them. My conclusion is that shavyei anafshei applies only to prohibitions and not to mitzvos.

(Originally featured in Mishpacha Issue 655)