Anaximander [611 - 547 B.C.]

Anaximander from Miletus (611 - 547 B.C.), was Thales's disciple. He perceived world in quite a simple way - as the composition of contrasts: dry and wet, hot and cold. You might think that quite a smart teacher had quite a silly disciple. Well... not exactly because Anaximander said that one contrast element couldn't came from the other and it would be a mistake to declare any one of them as a basic element. "So what" you may say again. So what?! Think! He found out that there is more than one basic substance. Nowadays we call them chemical elements. 

Think again! - There was a man living before Christ who knew that some things cannot change into others just as we today know that for example copper cannot be changed into gold and vice versa!
 

That is not all about him - he believed in the subsistence of substance he called "apeiron". He thought it was a great, infinite in time and space, undiverted and neutral immensity. Strange features? Well, as for us apeiron resembles something well known nowadays - vacuum! Of course Anaximander wasn't always that right: He said that apeiron filled the whole world and was a creative element of all the other substances which later disappeared in it. 

According to Anaximander oppositions included in apeiron could separate. What he also maintained is that matter was combined with motion making a unit.
And what do you think about him now?

More on Anaximander: Fragments

Anaximander of Miletos, son of Praxiades, a fellow-citizen and associate of Thales, said that the material cause and first element of things was the Infinite, he being the first to intro­duce this name for the material cause. He says it is neither water nor any other of the so-called elements, but a substance different from them, which is infinite, from which arise all the heavens and the worlds within them. And into that from which things take their rise they pass away once more, "as is ordained; for they make reparation and satisfaction to one another for their injustice according to the appointed time," as he says in these somewhat poetical terms. —Phys. Op. fr. 2 (R. P. 16). 

He says that the earth is cylindrical in form, and that its depth is as a third part of its breadth. He says that something capable of begetting hot and cold was separated off from the eternal at the origin of this world. From this arose a sphere of flame which grew round the air encircling the earth, as the bark grows round a tree. When this was torn off and enclosed in certain rings, the sun, moon, and stars came into existence.—Ps.-Plut. Strom. fr. 2 (R. P. 19).

He says that this is eternal and ageless, and that it encom­passes all the worlds.—Hipp. Ref. i. 6 (R. P. 17 a).

And besides this, there was an eternal motion, in the course of which was brought about the origin of the worlds. The earth swings free, held in its place by nothing. It stays where it is because of its equal distance from everything. Its shape is convex and round, and like a stone pillar. We are on one of the surfaces, and the other is on the opposite side. The heavenly bodies are wheels of fire separated off from the fire which encircles the world, and enclosed in air. And they have breathing-holes, certain pipe-like passages at which the heavenly bodies are seen. For this reason, too, when the breathing-holes are stopped, eclipses occur. And the moon appears now to wax and now to wane because of the stopping and opening of the passages. The circle of the sun is twenty-seven times the size (of the earth, while that) of the moon is eighteen times as large. The sun is highest of all, and lowest are the wheels of the fixed stars. Living creatures arose from the moist element as it was evaporated by the sun. Man was like another animal, namely, a fish, in the beginning.—Hipp. Ref. 1. 6 (R. P. 22 a).

Rain was produced by the moisture drawn up from the earth by the sun.—Hipp. Ref, i. 6, 7 (Dox. p. 560).

Further, there cannot be a single, simple body which is infinite, either, as some hold, one distinct from the elements, which they then derive from it, nor without this qualification. For there are some who make this (i.e. a body distinct from the elements) the infinite, and not air or water, in order that the other things may not be destroyed by their infinity. They are in opposition one to another—air is cold, water moist, and fire hot—and therefore, if any one of them were infinite, the rest would have ceased to be by this time. Accordingly they say that is infinite is something other than the elements, and from it the element arise. Arist. Phys. Γ, 5, 204 b 22 (R. P. 16 b).

Those who assumed innumerable worlds, e.g. Anaximander, Leukippos, Demokritos, and, a later date, Epicurus, held that they came into being and others passing away.

Anaximander said the stars were hoop-like compressions of air, full of fire, breathing out flames at a certain point from orifices. The sun was highest of all, after it came the moon, and below these the fixed stars and the planets.—Aetios, ii. 13, 7; 15, 6 (R P. 19 a).

Anaximander said the sun was a ring twenty-eight times the size of the earth, like a cart-wheel with the felloe hollow and full of fire, showing the fire at a certain point, as if through the nozzle of a pair of bellows.—Act. ii. 20, i (R. P. 19 a).

Anaximander said the sun was equal to the earth, but the ring from which it breathes out and by which it is carried round was twenty-seven times as large as the earth.—Aet. ii. 21, i (Dox. p. 351).

Anaximander said the moon was a ring eighteen times the size of the earth. . . .—Aet. ii. 25, i (Dox, p. 355).

Anaximander held that thunder and lightning were caused by the blast. When it is shut up in a thick cloud and bursts forth with violence, then the breakage of the cloud makes the noise, and the rift gives the appearance of a flash by contrast with the darkness of the cloud.—Aet. iii. 3, i (Dox. p. 367).

Anaximander held that wind was a current of air (i.e. vapour) which arose when its finest and moistest particles were set in motion or dissolved by the sun.—Aet. iii. 6, i (Dox. P- 374).

The sea is what is left of the original moisture. The fire has dried up most of it and turned the rest salt by scorching it—Aet. iii. 16, i (R. P. 20 a).

The first animals were produced in the moisture, each en­closed in a prickly bark. As they advanced in age, they came out upon the drier part   When the bark broke off, they survived for a short time.—Aet v. 19, i (R. P. 22).

He declares that at first human beings arose in the inside of fishes, and after having been reared like sharks, and become capable of protecting themselves, they were finally cast ashore and took to land.—Plut Symp. Quaest, 730 f (R. P. 22.).