Anaximenes of Miletus

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Anaximenes of Miletus

(fl. 546/545 b.c.)


The year in which Anaximenes is said to have flourished is that of the fall of Sardis. and therefore his chronology, which comes from Apollodorus, may be arbitrary. Anaximenes may or may not have been a student of Anaximander, but there can be no question that he was acquainted with Anaximander’s book, since his cosmological and astronomical views are very close to those of Anaximander. His interests, however, seem to have been more restricted than those of Anaximander; but like the latter, Anaximenes thought that the source from which all things come into being is infinite. He further qualified this original substance by saying that it is air, for he had discovered a mechanism that could account for the transformation of one thing into another: the mechanism of condensation and rarefaction. When air is evenly distributed, it is invisible; when it is condensed, it becomes water; and when it is condensed further, it becomes earth and then stone. When, on the other hand, air is hot, it becomes rarefied and eventually becomes fire. Anaximenes seems to have been satisfied that the following “experiment,” which proved to him that cold air is condensed and hot air is rarefied, corroborated his theory: When we expel air, it becomes cold if we press our lips, whereas it becomes hot if we open our mouths. This experiment, which is recounted—perhaps in Anaximenes’ own words—by Plutarch, shows that for Anaximenes air is a substance composed of small, discrete particles: when the particles are compressed, we have water; when they are expanded by heat, we have hot air, fire, etc. This substance thus composed of discrete particles is not more air than water, earth, or fire, but Anaximenes seems to have named it “air” because air is the most widely distributed body in the universe and because breath is identified with the soul, which he believed holds living beings together.

On the basis of this analogy, Anaximenes seems to have believed that the cosmos breathes by inhaling the surrounding air. Consequently, what Anaximenes calls air should not be identified with a single substance that by qualitative alteration becomes all the things we see around us—as Aristotle, Theophrastus, and the doxographers believed he meant. Anaximenes seems also to have believed in an infinite number of worlds that come into being and pass away, to be reabsorbed into the infinite air that surrounds them and is in perpetual motion. We also find in Anaximenes the use of rotatory motion to explain the formation of our world: the big masses of air and water and the heavenly bodies are formed through the process of condensation and rarefaction; the earth, a flat disk at the center, is supported by air; and the same annular form is attributed to the heavenly bodies, which are carried around and supported by air. Since for Anaximenes the sun and the moon are formed out of fire, he must have been ignorant of the fact that the moon reflects the light of the sun. The heavenly bodies turn around the earth and become invisible because they are so far away and because the northern parts of the earth are elevated.


The ancient sources are collected in Diels and Kranz, Die Fragmente der Vorsokratiker, 6th ed., I (Berlin, 1951), 90–96.

Modern works dealing with Anaximenes are J. Burnet, Early Greek Philosophy, 4th ed. (London, 1930), pp. 72–79; H. Cherniss, Aristotle’s Criticism of Presocratic Philosophy (Baltimore, 1935); W. A. Heidel, “The ΔINH in Anaximenes and Anaximander,” in Classical Philology, 1 (1906), 279–282; J. B. McDiarmid, “Theophrastus on the Presocratic Causes,” in Harvard Studies in Classical Philology, 61 (1953), 85–156; A. Maddalena, Ionici, testimonianze e frammenti (Florence, 1963), with bibliography; and R. Mondolfo, in E. Zeller and R. Mondolfo, La filosofa dei greci nel suo sviluppo storico, pt. 1 (Florence, 1938), 206–238, with bibliography.

L. TarÁn