Today at mass, we begin a sojourn thru the most important book in the O.T. (Hebrew Tanak), the Book of Exodus. This is the hub of the O.T. and the singular act that formed the Hebrews into a people, their deliverance from slavery in Egypt. Luke even calls what Jesus did in suffering and dying as His “exodus.” At the Easter Vigil, the reading from Exodus is the only O.T. reading that is required to be read.