"Scientific Knowledge is a mode of conception dealing with universals and things that are of necessity; and demonstrated truths and all scientific knowledge (since this involves reasoning) are derived from first principles. Consequently the first principles from which scientific truths are derived cannot themselves be reached by Science; nor yet are they apprehended by Art, nor by Prudence. To be matter of Scientific Knowledge a truth must be demonstrated by deduction from other truths; while Art and Prudence are concerned only with things that admit of variation. Nor is Wisdom the knowledge of first principles either: for the philosopher has to arrive at some things by demonstration."