To know what is first requires knowing its ratio or logos.
The ratio or logos of anythig is what an infinite mind intended it to be.
The human mind can only understand the intention of an infinite mind by a multitude of finite ideas it cannot reduce.
The logoi of things are their natural laws
God either is the natural law of thing, or that relative to which these laws are unified and intelligible, etc.
(example: nature clearly intends to work with phi, but we cannot reduce phi to something first.)
Thus, though we can seek what is first, this leads us not to a single ratio, since this is unintelligible to us, but to a multitude of logoi that each appear irreducibly first to us.