The Refutation of All Heresies: Book I. 8Anaximenes; His System of “An Infinite Air;” His Views of Astronomy and Natural Phenomena.

But Anaximenes, who himself was also a native of Miletus, and son of Eurystratus, affirmed that the originating principle is infinite air, out of which are generated things existing, those which have existed, and those that will be, as well as gods and divine (entities), and that the rest arise from the offspring of this. But that there is such a species of air, when it is most even, which is imperceptible to vision, but capable of being manifested by cold and heat, and moisture and motion, and that it is continually in motion; for that whatsoever things undergo alteration, do not change if there is not motion. For that it presents a different appearance according as it is condensed and attenuated, for when it is dissolved into what is more attenuated that fire is produced, and that when it is moderately condensed again into air that a cloud is formed from the air by virtue of the contraction; but when condensed still more, water, (and) that when the condensation is carried still further, earth is formed; and when condensed to the very highest degree, stones. Wherefore, that the dominant principles of generation are contraries,--namely, heat and cold. And that the expanded earth is wafted along upon the air, and in like manner both sun and moon and the rest of the stars; for all things being of the nature of fire, are wafted about through the expanse of space, upon the air. And that the stars are produced from earth by reason of the mist which arises from this earth; and when this is attenuated, that fire is produced, and that the stars consist of the fire which is being borne aloft. But also that there are terrestrial natures in the region of the stars carried on along with them. And he says that the stars do not move under the earth, as some have supposed, but around the earth, just as a cap is turned round our head; and that the sun is hid, not by being under the earth, but because covered by the higher portions of the earth, and on account of the greater distance that he is from us. But that the stars do not emit heat on account of the length of distance; and that the winds are produced when the condensed air, becoming rarified, is borne on; and that when collected and thickened still further, clouds are generated, and thus a change made into water. And that hail is produced when the water borne down from the clouds becomes congealed; and that snow is generated when these very clouds, being more moist, acquire congelation; and that lightning is caused when the clouds are parted by force of the winds; for when these are sundered there is produced a brilliant and fiery flash. And that a rainbow is produced by reason of the rays of the sun falling on the collected air. And that an earthquake takes place when the earth is altered into a larger (bulk) by heat and cold. These indeed, then, were the opinions of Anaximenes. This (philosopher) flourished about the first year of the lviii. Olympiad.