Menachot 38 - The Blue Thread in Tzitzit

"Blue" in the tzitzit, or "Tchelet", is wool that has been dyed with blue dye produced from "blood" (that is, inky secretion) of a rare Mediterranean sea creature known as chilazon. For many centuries, this dye was unavailable because the identity of the chilazon was forgotten. However, if the tzitzit (ritual fringes) is made completely of white strings, it is still valid.

The tzitzit should be made of two white threads and two blue threads, knotted together. If one made them of only blue threads, and omitted the white, this is also valid.

What if the threads are so thick that they cannot be tied in a slipknot, but they are long enough that had they been thin, they could have been tied in a slipknot? Said Rav Acha the son of Rava to Rav Ashi, "Certainly they are valid, for when the threads are thick, their fulfillment of the commandment is even more noticeable."

Art: Eugène Boudin - White Clouds, Blue Sky

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