(A cosmological argument that operates from the interesting assumption that the universe is a necessary being.)
C = what is conceivable to some mind. This means inter alia what can play the role of a true premise or conclusion in a coherent and true system. This is why complex numbers, four-dimensional space, and immaterial souls or angels are not picturable but are still C.
U = The totality of physical things. The universe or multiverse, whichever theory pans out. We operate under the hypothesis that it exists necessarily.
Assumption: there is not an infinite history of minds going back as long as there has been a U. As far as anyone can tell, this is wildly true and such minds only go back for a vanishingly small fraction of its existence.
1.) The possible is C. (axiom)
2.) C exists relative to a mind. (by definition)
3.) U is possible. (look around)
4.) U exists relative to mind. (1, 2, 3)
5.) If U exists relative to a mind that is not necessary then the universe is not necessary.
6.) U exists relative to a mind that exists necessarily. (consequent of 5 is contrary to hypothesis)