...through two lights... This is the nature of the developmental sequence (השתלשלות, hishtalshelut), whereby each light is emanated by and emerges from another light. It is caused by that light in accordance with the principle of gradation....that draw it forth.... The emanated light is a particular detail whose source is from the Supreme Will, this being the Master of all the powers, which are revealed by Him one by one.
Since He wanted to display things in a graded way, level by level, He instituted the entire developmental sequence so as to show in an orderly manner what comes first and what comes second. In order to display this continuity, it was necessary for one light to draw out another from the Supreme Source. This comes about through the mystery of new mental states (התחדשות המוחין, hitchadshut hamochin) and coupling (זיווג, zivug), as will be explained below in its appropriate place, with the help of heaven. (It is not that the lights which couple together bring the light they produce into existence, but rather, they draw it forth from the Supreme Source.)