Tekhelet

Aaron wearing a robe, as depicted in the 3rd century when a unique variant of violet-indigo (sagol, segol) (instead of skyblue, tekhelet) was still worn

In the early classical sources (Septuagint, Aquila, Symmachus, Vulgate, Philo, and Josephus), tekhelet was translated into Greek as hyakinthos (ὑακίνθος, "hyacinth") or the Latin equivalent.[26] The color of the hyacinth flower ranges from violet blue to a bluish purple (though the hyacinth species dominant in the eastern Mediterranean, Hyacinthus orientalis, is violet[26]), and the word hyakinthos was used to describe both blue and purple colors.[26]

Early rabbinic sources provide indications as to the nature of the color. Some sources describe tekhelet as visually indistinguishable from indigo (kala ilan).[28] This description is also somewhat ambiguous, as different varieties of indigo have colors ranging between blue and purple,[26] but generally the color of dyed indigo in the ancient world was blue.[29]

Other rabbinic sources describe tekhelet as similar to the sea or sky. An oft-repeated explanation for the Torah's choice of tekhelet went as follows: "Why is tekhelet different from all other colors? Because tekhelet is similar [in appearance] to the sea, and the sea is similar to the sky, and the sky is similar to lapis lazuli, and lapis lazuli is similar to the Throne of Glory."[30] (In a few versions of this source, "plants" (asavim) are included in this chain of similarity even though plants are not blue;[31] though it has been suggested that these sources refer to bluish plants like hyacinth.)[26] Jose ben Jose was another early author who described tekhelet as resembling the sky.[29]

In still other sources the color of tekhelet is compared to the night sky.[32] Similarly, Rashi quotes Moshe ha-Darshan who describes it as "the color of the sky as it darkens toward evening" – a deep skyblue or dark violet.[33]

Rashi himself describes the color as "green" (ירוק)[34] and "green, and close to the color of leeks",[35] the latter commenting on a Talmudic passage according to which the morning Shema may be recited once it is light enough to distinguish between tekhelet and leeks. Other Jewish texts comment that "the appearance which is called in the language of Ashkenaz bleu (בלו"א) is within the category of green (ירוק)"[36] suggesting that Rashi's language does not necessarily rule out a blue color.

In Akkadian, the cognate word takiltu is written using the word sign also used for lapis lazuli, suggesting they have similar colors.[25] Lapis lazuli can vary between blue and purple-blue, and according to some sources the preferred shade of lapis lazuli in the Near East was purple-blue.[25] However, Mesopotamian mythology asserted that visible sky is a layer of lapis lazuli stone underlying Heaven, suggesting a sky-blue color for the stone.[37]

The Sifrei says that counterfeit tekhelet was made from both "[red] dye and indigo", indicating that the overall color was purple.[38] However, other sources list just "indigo" as the counterfeit,[28] suggesting either that in their opinion the color was purely blue, or that indigo was the main counterfeit ingredient and the other ingredients not significant enough to mention.

The Sippar Dye Text (7th century BCE), as well as the Leyden and Stockholm papyri (3rd century) provide recipes for counterfeit takiltu dye that include a mixture of red and blue colors, for an overall purple color.[25]

A pure blue color can only be produced from Hexaplex dye through a debromination process. Only in the 1980s did modern scientists learn how to create blue Hexaplex dye using this process, leading some experts to declare that ancient dyers would not have been able to create blue tekhelet (and therefore, that an undebrominated purple color is more likely).[26] However, in recent years archaeologists have recovered several fabrics dyed blue with Hexaplex dye 1800 or more years ago, demonstrating that ancient dyers could and did make blue dye from Hexaplex.[29] Such fabrics have been found at Wadi Murabba'at (2nd century),[39] Masada (1st century BCE),[40] Qatna (14th century BCE),[41] and arguably[42] Pazyryk valley (5th-4th century BCE).[29]

Hexaplex trunculus found on Israeli coastal plain near Tel Shikmona

Hexaplex trunculus camouflated in sea fouling

Purple dye-bath with extracts from fresh Hexaplex trunculus glands

A guide from the Ptil Tekhelet Foundation shows how a piece of wool, dipped into the solution for the Hexaplex trunculus based dye, turns into leek-like green in sunlight, and eventually into (dark) blue with a purple hue.

In his doctoral thesis (London, 1913) on the subject, Rabbi Yitzhak HaLevi Herzog named Hexaplex trunculus (then known by the name "Murex trunculus") as the most likely candidate for the dye's source. Herzog concluded “it is very unlikely that the tekhelet-hillazon is not the snail called murex trunculus, but though unlikely, it is still possible.”[57][58] Though Hexaplex trunculus fulfilled many of the Talmudic criteria, Herzog's inability to consistently obtain blue dye (sometimes the dye was purple) from the snail precluded him from declaring it to be the dye source. In the 1980s, Otto Elsner,[59] a chemist from the Shenkar College of Fibers in Israel, discovered that if a solution of the dye was exposed to ultraviolet rays, such as from sunlight, blue instead of purple was consistently produced.[60] In 1988, Rabbi Eliyahu Tavger dyed Tekhelet from H. trunculus for the Mitzvah (commandment) of Tzitzit for the first time in recent history.[14]^: 23 Based on this work, four years later, the Ptil Tekhelet Organization was founded to educate about the dye production process, and to make the dye available for all who desire to use it. The television show The Naked Archaeologist interviews an Israeli scientist who also makes the claim that this mollusk is the correct animal. A demonstration of the production of the blue dye using sunlight to produce the blue color is shown. The dye is extracted from the hypobranchial gland of Hexaplex trunculus snails.[45]

Chemically, exposure to sunlight turns the red 6,6'-dibromoindigo in snails into a mixture of blue indigo dye and blue-purple 6-bromoindigo. The leuco (white) solution form of dibromoindigo loses some bromines in the ultraviolet radiation.[61]

The dye produced by Hexaplex has the exact same chemical composition as indigo,[19] corresponding to the statement that only God can distinguish the tekhelet from indigo garments.

In the area between Tyre and Haifa where the hilazon was found, piles of murex shells hundreds of yards long have been found, apparently the result of dying operations.[62] In Tel Shikmona (near Haifa), a "biblical era purple dye workshop" was found including relics of purple dye produced from sea snails, as well as textile manufacturing equipment.[63]

Chemical testing of ancient blue-dyed cloth from the appropriate time period in Israel reveals that a sea-snail based dye was used. Since murex dye was available, very long lasting, and visibly indistinguishable from indigo based dyes, but also not specifically prohibited against as counterfeit despite being known, it is argued that murex (or one of the other two indigo producing sea snails) must have been the hilazon or at least deemed as acceptable to use interchangeably.[64]

Hexaplex has a hard external shell, as the hilazon appears to.

The word Ḥillazon is cognate to the Arabic word halazuun, meaning snail.[65] Hexaplex opponents suggest that in ancient times the word might have referred to a broader category of animals, perhaps including other candidate species such as the cuttlefish.[66]

Another requirement according to the Talmud is that the dye cannot fade, and the Murex dye does not fade and can only be removed from wool with bleach.[67]

The Talmud states that the hillazon is preferably kept alive while the dye is extracted, as killing it causes the dye to degrade.[68] This matches both ancient descriptions of the Hexaplex dying process, and also modern experience that an enzyme in the snail needed for dye production decays quickly after death.[62][69]

The Jerusalem Talmud[70] translates tekhelet as porporin; similarly Musaf Aruch translates tekhelet as parpar. These translations refer to the Latin term purpura, meaning the dye produced by Hexaplex snails.[62] Similarly, Yair Bacharach stated that tekhelet was derived from purpura snails, even though this forced him to conclude that the color of tekhelet was purple rather than blue, as in his era it was unknown how to produce blue dye from Hexaplex.[62]

The word porforin, or porpora, or porphoros is used in the midrash as well as many other Jewish texts to refer to the Ḥillazon, and this is the Greek[71] translation of Murex trunculus. Pliny and Aristotle also both refer to the Porpura as being the source for purple and blue dyes, showing that the Murex has a long history of being used for blue dye.[23]

Deuteronomy 33:19 speaks of treasures hidden in the sand; the Talmud states that the word "treasures" refers to the Ḥillazon.[72] Similarly, Hexaplex trunculus often burrows into the sand, making it difficult to detect even by scuba divers.[62]

While (as described in the next section) Hexaplex arguably does not fit every textual description of the hillazon, nevertheless "Of the thousands of fish and mollusks that were studied to date, no other fish has been found that can produce the tekhelet color" which suggests that there is no more likely alternative species.[62]

The Talmud equates the colors of tekhelet and indigo, but also gives a practical test to distinguish between the two fabrics. Seemingly, since the color-producing compounds in Hexaplex trunculus and indigo are identical, no test should be able to distinguish them.[62][66] However, according to Professor Otto Elsner, while Hexaplex and indigo have the same color-producing compound, they also contain other compounds which differ and may lead to a different response in the practical test.[62] According to Professor Ziderman, the test consists of a chemical reduction reaction occurring when hydrogen is produced by decaying organic matter. Indigo (from a vegetable source) is more strongly reduced than the debrominated indigo found in snail tekhelet (assuming a blue-purple rather than pure blue tekhelet), leading to a different result to the test.[73]

The hillazon's body resembles the sea. This does not appear to be true of Hexaplex. Hexaplex supporters argue that when alive Hexaplex is well camouflaged and has a similar appearance to the sea floor, apparently due to algae which grow on its shell.[62] This shell color can even be blue, similar to the sea.[73]

The hillazon has a "form like a fish", which a snail seemingly does not. Hexaplex supporters reply that its shell somewhat resembles a fish in shape.[74] Similarly Maimonides, Tosafot, and Rashi say the Ḥillazon is a "fish" (דג), while Hexaplex is a snail rather than a fish. Hexaplex supporters argue that many forms of aquatic life (e.g., shellfish — of which sea snails would be an example) are also called "דגים" in Hebrew.[75]

The hillazon is said to come up from the sea once every 70 years. It is unclear what this is exactly referring to, but the Hexaplex has no such cycle.[66] Hexaplex supporters note that elsewhere the Talmud makes clear that the hillazon was also hunted by normal methods at other times.[54] Some sources say the reference to "70 years" does not imply a periodic cycle, but rather simply that this phenomenon is a rare event.[62] Hexaplex may have cycles of other lengths which inspired this statement: a seven-month cycle for harvesting Hexaplex was claimed by Pliny and confirmed by modern researchers, while Hexaplex appears to have a yearly behavioral cycle in which it burrows in the sand in summer and emerges to swim in winter.[73] Other sources claim that the 70-year cycle was a miraculous occurrence which no longer occurs, or else that the decrease in Hexaplex population numbers may have caused this behavior to cease.[62]

There are two other snails that produce the same dye as Hexaplex trunculus: Bolinus brandaris and Stramonita haemastoma, so how do we know which one is the Ḥillazon? Some argue that dye from any of these species would be valid. Alternatively: Hexaplex trunculus contains more natural indigo and thus is a more natural source for blue tekhelet, and archaeological finds show Hexaplex trunculus being processed separately from snails of the other species, suggesting that a different color was derived from this species.[69]

Trapping the Ḥillazon is a violation of Shabbat.[54] However, according to some rishonim, in general it is permitted to capture slow-moving animals like snails on Shabbat (as capturing them requires only a trivial effort - בחד שחיא).[76] This contradiction suggests that the hillazon is not a snail. Hexaplex supporters argue that since Hexaplex tends to camouflage itself and hide in the sand, capturing it is a difficult process and thus (by some opinions) forbidden.[62]

Rambam, describing the Ḥillazon, says that "its blood is as black as ink",[77] which is not true of Hexaplex. Hexaplex supporters argue that this statement has no apparent source earlier than Rambam, and appears to be based on a mistaken statement by Aristotle.[66] In any case, a black precipitate can in fact be derived from Hexaplex, which is then refined into dye.[73]

Tractate Menachot[78] and the Rambam explain the process for making the dye for tekhelet, and neither of them mention explicitly that it needs to be placed in the sunlight. Putting the dye in sunlight is a requirement to make the dye from the murex trunculus.[75]

The common cuttlefish

A sample of Prussian blue, a counterfeit blue

In 1887, Grand Rabbi Gershon Henoch Leiner, the Radziner Rebbe, researched the subject and concluded that Sepia officinalis (common cuttlefish) met many of the criteria. Within a year, Radziner chassidim began wearing tzitzit with cuttlefish dye. Herzog obtained a sample of this dye and had it chemically analyzed. The chemists concluded that it was a well-known synthetic dye "Prussian blue" made by reacting Iron(II) sulfate with an organic material. In this case, the cuttlefish only supplied the organic material which could have as easily been supplied from a vast array of organic sources (e. g., ox blood). Herzog thus rejected the cuttlefish as the Ḥillazon and some suggest that had Leiner known this fact, he too would have rejected it based on his explicit criterion that the blue color must come from the animal and that all other additives are permitted solely to aid the color in adhering to the wool.[79]

Within his doctoral research on the subject of Tekhelet, Herzog placed great hopes on demonstrating that Hexaplex trunculus was the genuine Ḥillazon. However, having failed to consistently achieve blue dye from Hexaplex, he wrote: “If for the present all hope is to be abandoned of rediscovering the Ḥillazon Shel Tekhelet in some species of the genera Murex [now "Hexaplex"] and Purpura we could do worse than suggest Janthina as a not improbable identification".[80] Janthina is a genus of sea snails, separate from Hexaplex. More recently, blue dye has been obtained from Hexaplex and the pigment molecule itself is hypothesized to be Tyrian Purple or Aplysioviolin.[81] Janthina seems an unsuitable candidate in several ways: it was apparently only rarely used by ancient dyers; it is found far out at sea (while the hilazon is apparently found near the coast); and its pigment is allegedly unsuitable for dying.[73]

In 2002 Dr. S. W. Kaplan of Rehovot, Israel, sought to investigate Herzog's suggestion that Tekhelet came from the extract of Janthina. After fifteen years of research he concluded that Janthina was not the ancient source of the blue dye.