Anaximenes of Miletus was a Pre-Socratic Philosopher, (585 BCE - 528 BCE). Like all Pre-Socratics, little remains of the work by Anaximenes and little is known in regards to the details of his life. It has been postulated that the philosopher was born around 585 BCE and died around 528 BCE. He is considered, after Thales and Anaximander, the third philosopher from what has come to be known as the Milesian school of philosophy, operating in the ancient Greek land of Ionia, or present day Turkey. Like his predecessors, Anaximenes was preoccupied with cosmology, searching for the world’s origin in which he is most known for his assertion that air is the most basic and originary material and the source of all things. In addition to this main concentration, Anaximenes also made studies in meteorology.
In the Milesian tradition, in which the members of the school are often referred to as being “material monists," Anaximenes sought to articulate one particular substance as responsible for all things. This of course diverts from Anaximander, presumably the young philosopher’s teacher, who postulated the notion of aperion—that which is indefinite and boundless—as the origin of the cosmos. Anaximenes disagreed with this notion of “an indefinite stuff" and believed that there must be a particular substance and that substance was air. Interestingly enough, his observation and understanding of air and it’s transformative properties actually positions his interpretation of the origin of the world in between that of Anaximander and Thales, the latter of whom considered water to be the essential element, rather then in direct opposition to either.
Air is the nearest to an immaterial thing; for since we are generated in the flow of air, it is necessary that it should be infinite and abundant, because it is never exhausted.
For Anaximenes, air was the essential element because it was, like Anaximander’s aperion, neutral and because it was infinite and always in motion. Air was everywhere, and everywhere it was transformable. It could transform into every other basic element, and hence everything else in the world. And this notion was an empirical one for Anaximander; he based his election of “air" on the observable fact that it transforms and his belief that it was the originary substance to transform into the other elements from which everything else could then be generated.
“[Air] differs in essence in accordance with its rarity or density. When it is thinned it becomes fire, while when it is condensed it becomes wind, then cloud, when still more condensed it becomes water, then earth, then stones. Everything else comes from these.”
Air, because it has such varying properties, is distinct and ideal as the candidate for an essential element according to Anaximenes. And, as he postulated, it was due to the fact that it has an innate means for transformation—condensation and rarefaction—that the element of air can produce and thus produces everything else. In effect, everything exists from varying densities of air itself. When air is condensed it becomes precipitation then water then earth then stone; when air is rarefied it becomes fire, which further rarefied becomes air, then wind, which can then precipitate again.
Interestingly, the oppositional aspects of hot and cold are present as in the Milesian tradition, but not as outside forces or things. Anaximenes was very dependent, and even radically dependent, on ‘empirical evidence’ regardless of how substantial. In defense of his theory for air as archê, Anaximenes observed that when one blows air through one’s mouth with pursed—condensed—lips, the air is cool (as in the case with hot food); when one blows air through one’s mouth with relaxed—rarefied—lips, the air is warm (as in the case of a ‘sigh’ or when warming cold hands). Thus hot and cold are present yet are ‘merely’ dependent upon the mode of transformation—condensation or rarefication.
While empirical evidence was essential in Anaximenes’ work, the less evidentiary notions of the divine remained apparent as well. Perhaps in line with early Greek literature that rendered air as the soul, as in the ‘breath of life,’ Anaximenes relates air with god and the divine, according to the accounts of Aetius. The qualities of air, that has similar attributes as the qualities of Anaximander’s aperion, are those of the divine and the eternal. It is posited, by Aetius and later by Cicero, that there is a strong correlation between the notion of air as an originary principle element and the notion of air and breath as the divine and eternal substance of the soul and of god.
Worldly and/or otherworldly, Anaximenes applied his theory of air to the cosmos as well. In his thinking, air formed the earth through a process similar to that of “felting" producing a flat disk that floated on air like a leaf. From evaporation, air was exhaled from the earth rarefied, which enabled it to become ignited producing the fiery celestial bodies of the stars. The moon and the sun were considered to be made up of air more condensed than rarefied, like earth. The sun’s fire was believed by Anaximenes to be a product of its high-speed motion rather then its composition of air. The celestial bodies were understood as floating, like earth, and imaged like a felt cap that could be pivoted around the head. In Anaximenes’ view, the sun’s setting was not attributed to its passing under the earth rather it was simply a case of it being obscured by higher parts of the earth’s form as the sun pivots around it.
Anaximenes elaborated on his theory to account for various other phenomena relating to more meteorological instances from rainbows to earthquakes. Rainbows were considered to be the result of the rays of the sun touching dense condensed air, essentially clouds. The severance of clouds by winds was thought to produce thunder and the flash of lightening. Earthquakes, Anaximenes surmised, were caused by an abundance of evaporation leaving the earth so dry it would crack or the opposite, an abundance of moisture causing cracks in the earth’s surface. He also provided a fairly accurate description of hail—frozen rainwater.
In particular, Anaximenes was quite influential being picked up by Heraclitus and critiqued by Parmenides. Anaxagoras will pull from his theory of materials while Plato will come to admire his understanding of change. Whether directly related or not, Diogenes of Apollonia will consider air as the principle element in his monistic theory.
While there are commentaries that claim Anaximenes and the Milesian school to be material monists presupposing Aristotle, a more accurate understanding of the Milesian tradition concludes that this is not the case. Anaximenes and the Milesian school were pre-occupied with discovering a particular element at the origin of the world yet it was not sought for or understood with the complexity that resulted from Aristotle’s metaphysics. It has been argued that the Milesian preoccupation with a singular originary material ‘stuff’ was related more to a material issue of powers than to a metaphysical issue of what substance is and how transformation relies on continuing causal substances that gain and lose properties. The latter is considered too advanced and complex for the kind of thinking and theorizing that the Pre-Socratics engaged it. Yet, Anaximenes, along with his predecessors, certainly paved the way for such thinking and philosophizing to occur. They are rather collectively the fathers of western philosophy.