This is a wonderful in depth teaching about the Tallit by Rabbi Fred Davidow
Blue has been a distinctive color of Judaism since Biblical times. In the Torah God commands the Israelites to wear a garment with fringes at each corner and to attach a blue thread to the fringes (Numbers 15:37-38). The blue dye used to color the wool came from the gland of a snail that lived in shallow waters off the coast of northern Israel.
It was the world’s most costly dye, since it took 12,000 snails to yield 1.4 grams of dye. The high cost of this dye is the reason why this bluish-purplish color became associated with royalty. Eventually the secret process of manufacturing the dye was lost or the snails were driven close to extinction by human rapacity.
The blue thread disappeared from the fringes but the color remained on the tallit as blue stripes. Hence we see on the flag of the State of Israel two broad blue stripes.
The tallit is worn only at Shacharit, the morning service, because the Torah states at Numbers 15:39 that, “it shall be to you a tassel to look upon and remember all the commandments of the Eternal.” The verbal phrase in the Hebrew text is u-r’item oto, which literally means, “you shall see it”. At dusk and during the night in the poorly lit homes and synagogues of ancient times it was virtually impossible to discern the color of the blue thread. Thus the commandment to see the blue thread could only be fulfilled in sunlight.
In traditional Judaism the observance of many rituals is determined by a specific time. The time to recite the Shema section of the liturgy in the morning is determined by the break of dawn, when the natural light of the sun returns. The Torah paragraph containing the commandment of the fringes with the blue thread is included within this Shema section of the siddur. The Talmud records a discussion among rabbis who were debating the question: How do we know when the night ends and the new day begins so that we can recite the Shema for the morning service? In the Mishnah Berakhot 1:2, Rabbi Eliezer says: "The night ends and the new day begins when you can tell the difference between a blue thread and a purple thread.” Rabbi Eliezer is saying that the proper time for the performance of the ritual of putting on the tallit is when there is sufficient light to distinguish between two colors next to each other on the spectrum. Thus halakhah (Jewish law) rules that we wear the tallit only at Shacharit, the morning service. Halakhah is developed by the “left brain” through the use of logic and analysis.
Aggadah (legend, lore), which taps into the “right brain” for feelings, presents ideas that speak to our hearts and motivate us to fulfill the moral values of Judaism. Here is an aggadic treatment of the question of when is the proper time to recite the morning Shema. In the Talmud, Berakhot 9b, a question is asked, “How do we know when the night ends and the new day begins? The answer supplied is: The night ends and the day begins at the time when one can see his friend from four feet away and recognize him.” This is the “right-brain” solution. This means more than being able to discern the color in the eyes of your friend. It points to the need to recognize in the face of your friend another soul created in the image of God and to treat that soul in a godlike way.
When people get stuck in bad attitudes, they are figuratively living in darkness. When the bad attitude gets broken, only then can a person see clearly and move toward recognizing and affirming his/her friends. We all need to see the faces of our friends and treat them with respect.