The Jews are a three part people. There are three kinds of Jews: the Priests (Cohanim), their assistants (Levites) and all the rest of the Jews.
Our Torah is a three part Torah. It is composed of the Torah (Five books of Moses), the Prophets, and the Writings (the five "scrolls").
And the Torah was given in three dimensions; in Space, in Time and in Soul. Soul is not a creation. It is the very essence of spirituality within the creation. It is G-dliness permeating the creation. Time and space come from G-d's "speech," but souls arose in His "thought." The Torah operates in the dimension of soul through the Jewish people, who are instructed to do His commandments (mitzvoth). Our intellect is also tri-partite. It is composed of Chabad - chochma (the initial flash of spiritual inspiration, bina (the ability to analyze the initial inspiration) and da'at (the ability to incorporate and utilize our new intellectual awareness).
The Zohar says that three are connected together: The Torah, the Jews and the One above. The connection is both external and internal. The more that we understand about space, time and soul, in the Torah, the more oneness and unity we bring to the world.