Anaximander (c. 610 - c. 546 BCE) of Miletus was a student of Thales, and recent scholarship argues that he, rather than Thales, should be considered the first western philosopher owing to the fact that we have a direct and undisputed quote from Anaximander while we have nothing written by Thales of Miletus. Anaximander invented the idea of models, drew the first map of the world in Greece, and is said to have been the first to write a book of prose. He traveled extensively and was highly regarded by his contemporaries. Among his major contributions to philosophical thought was his claim that the 'basic stuff' of the universe was the apeiron, the infinite and boundless, a philosophical and theological claim which is still debated among scholars today and which, some argue, provided Plato with the basis for his cosmology.
Of those who say that it is one, moving, and infinite, Anaximander, son of Praxiades, a Milesian, the successor and pupil of Thales, said that the principle and element of existing things was the apeiron [indefinite or infinite] being the first to introduce this name of the material principle. He says that it is neither water nor any other of the so-called elements but some other apeiron nature, from which come into being all the heavens and the worlds in them. And the source of coming-to-be for existing things is that into which destruction, too, happens 'according to necessity; for they pay penalty and retribution to each other for their injustice according to the assessment of time,' as he describes it in these rather poetical terms. It is clear that he, seeing the changing of the four elements into each other, thought it right to make none of these the substratum, but something else besides these; and he produces coming-to-be not through the alteration of the element, but by the separation off of the opposites through the eternal motion. (Physics, 24)
This statement by Anaximander regarding elements paying penalty to each other according to the assessment of time is considered the oldest known piece of written Greek philosophy, and its precise meaning has given rise to countless articles and books.
Thales claimed that the First Cause of all things was water but Anaximander, recognizing that water was another of the earthly elements, believed that the First Cause had to come from something beyond such an element. His answer to the question of 'Where did everything come from?' was the apeiron, the boundless, but what exactly he meant by 'the boundless' has given rise to the centuries-old debate. Does 'the boundless' refer to a spatial or temporal quality or does it refer to something inexhaustible and undefined?
While it is impossible to say with certainty what Anaximander meant, a better understanding can be gained through his 'long since' argument which Aristotle phrases this way in his Physics,
Some make this [First Cause] (namely, that which is additional to the elements) the Boundless, but not air or water, lest the others should be destroyed by one of them, being boundless; for they are opposite to one another (the air, for instance, is cold, the water wet, and the fire hot). If any of them should be boundless, it would long since have destroyed the others; but now there is, they say, something other from which they are all generated. (204b 25-29)
In other words, none of the observable elements could be the First Cause because all observable elements are changeable and, were one to be more powerful than the others, it would have long since eradicated them. As observed, however, the elements of the earth seem to be in balance with each other, none of them holding the upper hand and, therefore, some other source must be looked to for a First Cause. In making this claim, Anaximander becomes the first known philosopher to work in abstract, rather than natural, philosophy and the first metaphysician even before the term 'metaphysics' was coined.
Proto-theory of Evolution & the First Map
Anaximander has been credited with a proto-theory of evolution, as these passages attest:
Anaximander said that the first living creatures were born in moisture, enclosed in thorny barks and that as their age increased they came forth on to the drier part and, when the bark had broken off, they lived a different kind of life for a short time. (Aetius, V, 19)
He says, further, that in the beginning man was born from creatures of a different kind because other creatures are soon self-supporting, but man alone needs prolonged nursing. For this reason he would not have survived if this had been his original form. (Plutarch, 2)
And, further, is credited with drawing the first map:
Anaximander the Milesian, a disciple of Thales, first dared to draw the inhabited world on a tablet; after him Hecataeus the Milesian, a much travelled man, made the map more accurate, so that it became a source of wonder. (Agathemerus, I, i)
He charted the heavens, traveled widely, was the first to claim that the earth floated in space, and the first to posit an unobservable First Cause (which, whether it influenced Plato, certainly shares similarities with Aristotle's Prime Mover). Diogenes Laertius writes, "Apollodorus, in his Chronicles, states that in the second year of the fifty-eighth Olympiad, [Anaximander] was sixty-four years old. And soon after he died, having flourished much about the same time as Polycrates, the tyrant, of Samos." A statue was erected at Miletus in Anaximander's honor while he lived and his legacy still lives on centuries after his death.