Various explanations have been proposed for the rationale of how and why the universe exists and manifests itself as it does, with the detail and order that is obvious on the one side, and the virtually limitless fantasy of forms we see on the other.
“A first possible explanation points to a self-organising dynamic Chance that is at work, — a paradox necessitated by the appearance of inevitable order on one side, of unaccountable freak and fantasy on the other side of the cosmic phenomenon we call Nature.”
The implication here is that there is some womb of “possibilities” that gives rise to endless variations in actual manifestation. This of course still does not explain the origin and basis of the Energy that causes this manifestation.
And further, the question of random Chance comes up against the very strict rules and order that can be seen at each level of the manifestation, just below the surface variations.
A second option that has been proposed is that Nature has been formed to implement some mechanical laws or rules and it simply is a type of “machinery” in that sense. While this viewpoint accounts for the order of the universe, it does not come close to explaining the endless fantastic variations that we see in the untold number of forms that arise as life unfolds. This theory also cannot account for the arising of consciousness out of inconscience, because it would seem impossible for something to develop if it were not there and were just the result of a machinery at work. One would rather expect the machinery to replicate the forms of its machinery than to develop sentience that exceeds the earlier forms.
reference: Sri Aurobindo, The Life Divine, Book 2, Part I, Chapter 1, Indeterminates, Cosmic Determinations and the Indeterminable