ANAXIMENES (’Αναξιμενης) of Miletus, son of Euristratos, disciple and companion of Anaximander; the dates of his birth and death are unknown—according to the report of Apollodoros he was at his peak (’ακμη [akmé]) around 546 or 545 BC.
There is no information available on his life. He was the author of a work which has perished. The work was written in a simple and unpolished style and had the title On nature (Περι φυσεωσ [Peri physeos]), although the title was probably assigned to it later. The main points and some fragments of the work have been passed on by his doxographers: Aristotle, Theophrastus, Cicero, Pseudo-Plutarch, Hippolytus, and Simplicius. He was considered to be one of the “physicists” along with Thales and Anaximander, the circle of philosophers of the Ionian philosophy of nature who sought after the first principle and cause of all reality which they conceived of as a material principle—the arché (’αρχη).
Anaximenes, largely on the basis of his observations of phenomena, held that there is one principle. This principle is quantitatively infinite, eternal, ungenerated, and contains the source of its own motion and the cause of changes. However, unlike Anaximander’s apeiron (το ’απειρον [to apeiron]), Anaximenes thought that the principle had definite qualities and identified it with air (το ’αηρ [to aér]). As a principle the air is imperceptible because in its primordial and pre-phenomenal state it is equal in measure, uncondensed, and undiluted. The existence of air becomes apparent in the phenomena of cold, heat, wetness, and motion. As a result of its immanent motion, the first opposites emerge from the air (τα ’εναντια [ta enantia]): heat (το θερμον [to thermon]) which results from rarefaction; and cold (το ψυχρον (to psychron]) which results from the condensation of air. These opposites give rise to the sun, earth, water, winds, and meteorological phenomena. The world with everything in it is thus a principle that does not lose its fundamental definite character but only changes in its state of concentration. For Anaximenes air has a divine nature, both as a force that permeates the elements and bodies, and because the gods arose from the air. As the first of the Ionian philosophers of nature, Anaximenes described the status of the soul (ψυχη [psyché]) and its function in the body as a breath of air (το πνευμα [to pnéuma]) that is the principle of life. The celestial bodies arose from the earth. Vapors came out of the earth and then by rarefaction transformed into fire, and the stars are composed of fire. The earth is flat and is lifted up in the air.
Diels-Kranz I–III, J. Burnet, Early Greek Philosophy, Lo 1892, 19524; G. S. Kirk, J. F. Raven, M. Schofield, The Presocratic Philosophers, C 1957, 19832 (in Polish:Filozofia przedsokratejska, Wwa-Pz 1999).