Or la-Yesharim [“Light to the Just”: Novellae to Talmudic Tractate Pesachim] / Sepher Pethil Techeileth [“A Thread of Blue”: polemic against recently Innovated Radzyner Techeileth]

In the year 1888, Gershon Hanoch Leiner, the iconoclastic Chassidic Rebbe of Radzyn, published his work Pethil Techeileth, in which he announced his discovery in Italy of the mythical “chilazon” or sea -creature, which according to the Talmud, was the source of the long-lost “thread of blue” to the ritual fringes (tzitzith), as per Biblical mandate (see Numbers 15:38, and Rashi’s commentary ad loc.) This daring innovation met with stiff resistance in rabbinic circles, indeed one of the most vociferous opponents of the Radzyner techeileth was the flamboyant R. Hillel Moses Gelbstein of Jerusalem (a devout chassid of the Kotzker Rebbe, Menachem Mendel Morgenstern, and after the latter’s death, of R. Menachem Mendel Schneersohn of Lubavitch (“Tzemach Tzedek”). Besides mustering cogent arguments from Halacha and Kabbalah to refute Leiner’s discovery, Gelbstein eventually went so far as adopting vigilante tactics, burning tthe blue tzitzith together with the prayer shawls to which they were attached