Aristotle

“ Now when we ask about the fact, or enquire whether the thing has absolute existence, we enquire whether it has a middle term, but when we have learned the fact and solved the question as to its absolute or partial existence, then we ask what the middle term is. My phrase ‘partial existence’ would be illustrated by the questions ‘Does the moon wax?’ or ‘Is the moon eclipsed?’ In questions of this sort we do really ask whether a thing exists or not. ”

“ If, however, we were on the moon we should not enquire whether an eclipse does occur, nor yet why it occurs, for the answers to both these questions would become visible simultaneously. We should in fact have learned the universal as a result of sense perception. Sense perception would shew that the earth was at a particular moment excluding the sun’s light; and since it would also be obvious that the moon was then being eclipsed, knowledge of the universal would have been attained immediately. Thus, as we have said, knowing the nature of a thing is the same as knowing its cause. ”