The Mind And The Body

Knowing that logic metaphysically dictates truth, allows for absolute certainty, and is the thing one inescapably, constantly relies on is not the same as knowing that logic metaphysically exists independent of one's mind as a separate, self-necessary thing--and that it is the only thing that cannot not exist.  Not even God's nature as the uncaused cause entails this sort of absolute, intrinsic necessity, and the physical universe which relies on God for its creation is even further removed from this kind of utterly necessary existence because the alternative is impossible by default.  The laws of logic are the supreme metaphysical existent and are grasped on a constant basis by the human mind, though only the bare minimum grasp required to be aware of anything and to have the capacity to understand logical axioms onward is possessed by all people, with or without intentional effort to know these truths.

As for the universe, while it appears to be a vast, expanding group of matter that one can see by merely opening one's eyes, so much knowledge about it is locked behind epistemological limitations.  Knowing that one appears to have a body because of various visual experiences is not the same as knowing that one has a body or why this is knowable, albeit extremely unlikely to be discovered by most people.  It is rather difficult to initially discover the sole possible way to prove in spite of human limitations that matter does indeed exist: recognizing the immateriality of consciousness means one could eventually realize that physical sensations, unlike visual or audial perceptions, are logically impossible without a physical shell to experience them.  An immaterial seat of perception cannot experience tactile sensations, even if those sensations do not accurately convey things like the true weight or texture of external objects.

One's body, however, is both part of the physical world in all of its diversity and is but one small part detached from even the environment it stands on, unique in that it houses human consciousness.  One's mind, without which the body and other material stimuli (real or just perceived) could not even be perceived as illusions, is the more epistemologically fundamental of the two by far, for its existence is self-evident due to the logical impossibility of doubting or denying that it exists without already relying on its existence in order to even mistakenly think it is an illusion.  Both can be proven to exist, however.  The mind is just directly obvious once a person makes no assumptions and looks to the self-necessitating truth of logic to reveal this fact.  The body is not likely to truly be known to exist by as many people because the numerous precise factors which are not self-evident or true in themselves like logical axioms or introspective clarity.

The mind and the body nonetheless "grab" onto metaphysically similar to themselves in a certain way.  The immaterial mind grasps the immaterial, necessary truths of reason and the physical body can grasp other objects made of physical matter, although the very size of the external world and the existence of many objects that seem to exist within it are not logically provable.  In this sense, a like thing is the means by which one can know a like thing exists (even though knowing matter exists, like knowing anything at all, relies on logic as well even though reason is distinct from the physical world it governs).  Despite the fact that reason alone is metaphysically and epistemologically universal and thus dictates and reveals truths about even the external world itself, the mind and the body each grasp something external to themselves that is respectively immaterial or physical.