Know that the difficulties which lead to confusion in the question what is the purpose of the Universe or of any of its parts, arise from two causes: first, man has an erroneous idea of himself, and believes that the whole world exists only for his sake; secondly, he is ignorant both about the nature of the sublunary world, and about the Creator's intention to give existence to all beings whose existence is possible, because existence is undoubtedly good.
Your purpose...should always be to know...the whole that was intended to be known.
The question, "What is the purpose thereof?" cannot be asked about anything which is not the product of an agent; therefore we cannot ask what is the purpose of the existence of God.
The philosophers likewise assume that in Nature there is nothing in vain, so that everything that is not the product of human industry serves a certain purpose, which may be known or unknown to us.