The "four causes" are elements of an influential principle in Aristotelian thought whereby explanations of change or movement are classified into four fundamental types of answer to the question "why?". Aristotle wrote that "we do not have knowledge of a thing until we have grasped its why, that is to say, its cause." While there are cases where identifying a "cause" is difficult, or in which "causes" might merge, Aristotle held that his four "causes" provided an analytical scheme of general applicability.I must have learned about Aristotle's Four Causes in high school or university. And I certainly was aware of them later because I recall trying to reconcile how Aristotle's Four Causes were the same and/or different from the Five Whys in process improvement which likely would have been sometime in the late eighties, possibly the early nineties.
Matter: a change or movement's material cause, is the aspect of the change or movement which is determined by the material that composes the moving or changing things. For a table, that might be wood; for a statue, that might be bronze or marble.
Form: a change or movement's formal cause, is a change or movement caused by the arrangement, shape or appearance of the thing changing or moving. Aristotle says for example that the ratio 2:1, and number in general, is the cause of the octave.
Agent: a change or movement's efficient or moving cause, consists of things apart from the thing being changed or moved, which interact so as to be an agency of the change or movement. For example, the efficient cause of a table is a carpenter, or a person working as one, and according to Aristotle the efficient cause of a boy is a father.
End or purpose: a change or movement's final cause, is that for the sake of which a thing is what it is. For a seed, it might be an adult plant. For a sailboat, it might be sailing. For a ball at the top of a ramp, it might be coming to rest at the bottom.
But it is an odd sensation to see something you know you know something about but you also have not given a thought to in decades; to the point of having forgotten about, absent a prompt. A weird chimera of something you both recognize and yet no longer really know.