Note 18 — Chapter VI · THE STUDY OF NATURE. FUNDAMENTAL POSITIONS.

B. Elements. In expanding their views on the origin of the world, the Stoics begin with the doctrine of the four elements,18 a doctrine which, since the time of Aristotle and Plato, was the one universally accepted. They even refer this doctrine to Heraclitus, desiring, above all things, to follow his teaching in natural science.19 On a previous occasion, the order and the stages have been pointed out, according to which primary fire developed into the several elements in the formation of the world.20 In the same order, these elements now go over one into the other. Yet, in this constant transformation of materials, in the perpetual change of form to which primary matter is subject, in this flux of all its parts, the unity of the whole still remains untouched.21 The distinctive characteristic of fire is heat; that of air is cold; that of water, moisture; dryness that of the earth.22 These essential qualities, however, are not always found in the elements to which they belong in a pure state,23 and hence every element has several forms and varieties.24 Among the four essential qualities of the elements, Aristotle had already singled out two, viz. heat and cold, as the active ones, calling dryness and moisture the passive ones. The Stoics do the same, only more avowedly. They consider the two elements to which these qualities properly belong to be the seat of all active force, and distinguish them from the other two elements, as the soul is distinguished from the body.25 In their materialistic system, the finer materials, as opposed to the coarser, occupy the place of incorporeal forces.