The material/substance of being that doesn’t change, but subsumes all change… that which/who can willfully reclaim/renew … or bring to development/fruition … via willful change/action … is that which/who never changes. Anyone who can do that has something that never changes about them. An identity.
Reason why, reason how, and reason what are three different things, and all are required… distinctly. Aristotle‘s four causes and three substantia maintain the difference between matter — or what it is (which is dually considered an explanation or reason or cause… the material cause) — and form — or why it is (which is dually considered one of the three substantia) — and instead of an efficient cause being the third substantia, he had a composite of matter (what) and form (why) …. and some “blame” this how (willful change/action) on Descartes, heh, while simultaneously claiming that he left it (how) out. Was he being ironic…or were/are they?