Substantial Existance

Substantial Existance is a term that identifies a living beings ability to live in a given place or time.

Why one can not simply Exist.
Existance is a living beings ability to simply exist where it is. One can float in the Expanse and simply never reach The Path, while one can Exist in the Expanse, Substantial Existance is impossible, For simple Existance to be Substantial, one must be able to live and thrive in the place where they are located. While the requirements for a given race may change according to its bioligy, the term itself will not.