A Thread of Blue: How the lost colour of the Torah was found again, and why it may belong on your tzitzis

A Thread of Blue How the lost colour of the Torah was found again, and why it may belong on your tzitzis Twice a day, every day, we say that the Torah asked for a thread of techeiles on the corner of the garment. Then we look down at the corner and there is no blue there. Most of us have never asked why. This book is about one string. It was lost, and the reason is not a mystery. Techeiles came from a sea creature the Gemara calls the chilazon, worked by specialists on one stretch of the Mediterranean coast, and it cost so much that the Torah's own list puts it next to gold. Rome wanted that colour and took it. The coast was fought over, the Arab conquest came, and the last handful of licensed workshops did not survive it. Nobody abolished techeiles. There is no teshuvah anywhere setting it aside. It simply stopped, and the batei midrash wrote down what was left: and now we have only white. Then, over the last hundred and fifty years, it came back. Five people each supplied a piece of the puzzle, and none of them was working with the others or trying to solve it. A French zoologist worked out which Mediterranean snails give a permanent dye. A Chassidishe Rebbe went to an aquarium in Naples and came home convinced. An Irish Chief Rabbi took that dye to a laboratory and showed what it really was. A German chemist worked out the molecule. And an Israeli textile professor found that sunlight turns the purple into blue. Since 1985 it has been made again, and today you can buy it in Yerushalayim for about the price of a decent sefer. So the question this book exists to answer is whether that blue string is the one the Torah asked for. It is a real question, and serious people come down on both sides of it. Rav Yosef Sholom Elyashiv zt"l declined to rule on it. Rav Moshe Sternbuch shlita holds it is not correct. Rav Moshe Mordechai Karp shlita holds that anyone who has clarified the matter and concluded positively is obliged to wear it. All three are here at length, in their own words. Yehuda Davis started out knowing nothing about any of it, and wrote down what he found so that somebody else could reach an informed decision faster than he did. Six parts take you through the mitzvah, how it was lost, the search that recovered it, the evidence, the halacha, and then the practical end of it: which strings, how many, how to tie them, what it costs, and what to say when somebody in shul asks. One full chapter is given to the places where the case is weakest, and the halachic opposition is quoted at full strength before anybody answers it. Six appendices follow, and the last of them is a straight list of everything in the book that still needs checking. You do not need to read Hebrew. Every source is printed with full vowels and translated on the spot, and every reference sits in the text where it belongs. He wears techeiles, and he says plainly why he thinks you should too. He is also not a posek, and this is not a psak. You decide for yourself.