Let’s say you decide to take on a new good resolution. If you do it once—beginner’s luck. Twice—still beginner’s luck. If you do it three times then we can trust you.

So the number three represents permanence. That’s why we do things in threes, since it adds strength to our acts. (For example, many prayers are repeated three times; the Lulav is waved three times in each direction; etc.)

From a Kabbalistic perspective, we know that three is the number of peace and integration. The number two represents difference, division—right and left, giving vs. restraint.

Three, represents the integration of one and two. (The integration of giving vs. restraint, for example, results in one withholding a knife from a child who really wants to play with one.)

The Talmud¹ points out that the Torah was given in the third month of the Jewish year, to a people that has three groups (Kohen, Levite, Israelite), and through Moses, who was the third child in his family (after Miriam and Aharon). The (Written) Torah itself is made up of three portions: the Five Books of Moses, the Prophets and the Writings.

Torah is the manual for peace². It teaches how to integrate body and soul, the physical world with its spiritual source. It is "the third" entity, the one that unites the other two.