Pure reason reveals all, beginning with metaphysics and ending with spirituality. It explains everything in between and everything beyond.

The science of metaphysics, like all of knowledge, is fundamentally based upon the phenomenon of self-evidency. This means: axiomatic concepts which lead to knowledge and certainty. No synthetic or a priori phenomena exist or are true.

Self-evident truths are universally and necessarily true. All subsequent truth -- metaphysical, scientific, and otherwise -- is derived from a logical rational analysis of the various facts and evidence, leading then to proof and certainty. All truths are ultimately based upon (physical) sensation and (mental) reason.

The only two sources of knowledge in the universe, fundamentally, are sensation and reason.

All sensation yielding knowledge -- indeed, all sensation whatsoever -- takes place within and over space and time. Insensate intuition yields no knowledge and does not even exist. The universe and Nature is constituted such that nothing happens inside it without manifesting itself as, and taking the form of, events inside space and time. All change and becoming in the universe is thus. And reason sees it all.

There are various categories of rational understanding. The categories of quantity are: nullity, singularity, plurality, totality, and infinity. The categories of quality are: existence/truth, nonexistence/falsity, and uncertainty/ambiguity. The categories of relation are: essential qualities and inessential qualities. The categories of modality are: existence-nonexistence, necessity-optionallity, possibility-impossibility.

The principles of science and metaphysics are all truly, solidly, and definitively based upon self-evidency, sensation, and reason. Pure reason is the only kind of reason that exists and it yields all truth.