G. Speculations about the Cause Which Prompted the Formal Declaration of the Characteristics of the Tekhelet-hillazon

What may have been the occasion of this formal declaration of the hillazon-tradition? Was it an attempt made in certain quarters to replace the traditional hillazon-shel-Tekhelet by some other species? Or does the baraitha owe its origin to a desire on the part of the Jewish authorities to enlighten the general public with regard to the true nature of the Tekhelet dye in view of a widely prevalent error that kala-ilan (vegetable dyestuff producing a Tekhelet-like colour) might do for Tekhelet shel tzitzit? Or again, does the description simply represent an halakhah pure and simple taught in the academies as explanatory of the halakhah dating from hoary antiquity:תכלת אלא בחלזון אין צובעין “Tekhelet is not kasher (ritually fit), except if dyed with the blood of the hillazon” There is, I think, some ground for supposing that the baraitha represents an epistle sent to the diaspora (גולה) either for the purpose of enlightening extraPalestinian Jewry, or in direct answer to the inquiry about the identity of the hillazon-shel-Tekhelet. The final statement לפיכך דמיו יקרים “Therefore (i.e., because of the rarity of the species) it (Tekhelet) is very dear” would have been a superfluity in an halakhah taught at a Palestinian academy. The hearers of the lecture would be as cognisant of the cause of the expensiveness of Tekhelet as the lecturer himself. In an ordinary discourse the point might well be mentioned but in a formal concise halakhah it would be rather out of place. If, on the other hand, the baraitha was primarily intended for the information of the exiled communities, the case would be different. People buying at an exorbitant price Tekhelet sheltzitzit sent from the Holy Land might be eager to learn the reason of the high expensiveness of the article.