I shall further mention the moments of the real process in relation to motion, in which Aristotle finally passes on (De gen. et corr. II. 2-4) to the “principles of perceptible body”; we here see the elements in process, as formerly in their restful determinateness. Aristotle excludes the relations which concern sight, smell, &c., and brings forward the others as being those which are of sensible weight or lightness. He gives as these fundamental principles—warmth and cold, dryness and moisture; they are the sensible differences for others, while weight and lightness are different for themselves. Now in order to prepare for the transition of the elements into sensible relations, Aristotle says: “Because there are those four principles, and four things have properly six relations to one another, but the opposite cannot here be connected (the moist cannot be connected with the dry, or the warm with the cold), there are four connections of these principles, warm and dry, warm and moist, cold and moist, cold and dry. And these connections follow those first elements, so that thus fire is warm and dry, air warm and moist (vapour), water cold and moist, earth cold and dry.” From this Aristotle now makes the reciprocal transformation of the elements into one another comprehensible thus: Origination and decay proceed from the opposite and into the opposite. All elements have a mutual opposite; each is as non-being to the Being of the other, and one is thus distinguished from the other as actuality and capacity. Now amongst these some have an equal part in common; fire and water, for example, have warmth; thus if in fire dryness were overcome by moisture, out of fire air would arise. On the contrary, as regards those which have nothing in common with one another, like earth, which is cold and dry, and air, which is warm and moist, the transition goes more slowly forward. The transition of all elements into one another, the whole process of nature, is thus to Aristotle the constant rotation of their changes. This is unsatisfactory, because neither are the individual elements comprehended nor is the remainder rounded into a whole.