Answer: Wearing techeles was always an integral part of the mitzva of wearing tzitzis. Unfortunately, however, the art of making techeles from the chilazon has been lost for close to 2,000 years. The Midrash (Tanchuma, Shelach) laments that “now we have no techeles, only white, as techeles has been hidden.” While the Tosefta (Bava Metzia 61:) writes that one who doesn’t wear techeles has transgressed the mitzva of tzitzis, we see in the Gemara (Bava Metzia 61b and Menachot 40a, 43a) that wearing the wrong techeles invalidates the tzitzis.
But what is the chilazon? In the 1880’s, the Radzyner Rebbe, R’ Gershon Henoch Leiner, maintained that a particular squid (Sepia officinalis) was the long lost chilazon. He published 3 seforim on the subject, though while many used this dye to make techeles, it was far from blue and white! In 1913, R’ Issac Herzog published his doctoral thesis on techeles, naming a mollusk (Murex trunculus) as the most likely candidate for the source of techeles. The debate continues to this day.
While R’ Herzog’s arguments are most compelling, the Beis Halevi (R’ Yosef Ber Soloveitchik, 1820-1892) maintained that as the techeles has been lost from our mesorah, tradition, it should not be reinstated, irrespective of the evidence.
It is certainly no simple matter to reinstate a ‘lost tradition:’
While Kohanim duchen daily (Birchas Kohanim) in Eretz Yisrael, in chutz la’aretz this mitzva is reserved for Yom Tov. Various reasons have been given for this, including our lack of true simcha in the Diaspora. Nonetheless, many gedolim including both the Vilna Gaon and his student, R’ Chaim of Volozhin unsuccessfully tried to reinstate the daily beracha. The Aruch Hashulchan (OC 128:64) writes that it’s as if there was a voice from heaven calling out against reinstating it.We eagerly await the day when the true glory of these Mitzvos will be reinstated for all.