The fundamental idea is that even though the purpose of the lights as a whole was to bring forth separate creations, this had to be done gradually and not directly from the supernal Sefirot. The Sefirot were what the Eyn Sof blessed be He wanted to bring forth in order to create the separate creations. However, each one had to be on a level suited to the offspring it was to bring forth. This was what necessitated all the different graded levels, repairs, concealments and revelations – all in order to bring the light to a level fitted to bring forth its offspring.