Anaximenes of Miletus may have been a younger contemporary of Anaximander, whose pupil or friend the ordinary tradition represents him to have been. To him it seemed that the air, with all its variety of contents, it universal presence, and all the vagueness which it it has for the popular fancy as fpr the apparent source of life and growth, was what maintained the universe, even as breath, which is our life and soul, sustains us. This vital air, boundless in its kind, is the source of the world's life. Everything at a different degree of intensity. Eternal movement pervades it; and under the influence of heat, which expands, and cold, which contracts its volume, it gives rise to the several phases of existence. The process is a gradual one, and takes place in two directions, as heat and cold predominates. In this way was formed a broad disk of earth, which floats like a leaf on the circumambient earth. Similar condensations produced the sun and the stars; and the flaming state of these bodies is due solely to their extreme velocity of their motions. (See Ritter et Preller, Historia Phil. sect. 23-27; Mullach, Fragmenta Phil. Graec. i. 241-243.)
The above article was written by William Wallace, M.A., Merton College, Oxford University, 1867; Whyte's Professor of Moral Philosophy, Oxford University, from 1882; author of The Logic of Hegel, Epicureanism, Kant, and the Life of Arthur Schopenhauer.