Natural Philosophers / Pre-Socratics from Sophie’s World

by Catherine Chiu

Thales (Miletus)

  • ‘All things are full of gods.’
  • He calculated the height of a pyramid by measuring it’s shadow at the precise moment when the length of his own shadow was equal to his height.
  • He accuractely predicted a solar eclipse in the year 585 B.C.
  • The source of all things was water.

Anaximander (Miletus)

  • He thought that our world was only one of a myriad of worlds that evolve and dissolve in something he called the boundless.

Anaximenes (Miletus, c. 570 – 526 B.C.)

  • The source of all things was air or vapor. This was similar to Thales’ but he thought that water was condensed air.

Parmenides (Elea, c. 540 – 480 B.C.)

  • Everything that exists had always existed. Nothing could become anything other than what it is. Nothing can come out of nothing and nothing that exists can become nothing.
  • When forced to choose between relying either on his senses or his reason, he chose reason. He believed that our senses give us an incorrect picture of the world, a picture that does not tally with our reason.

Heraclitus (Ephesus, c. 540 – 480 B.C.)

  • ‘Everything flows.’ Constant change, or flow, was in fact the most basic characteristic of nature.
  • ‘God is day and night, winter and summer, war and peace, hunger and satiety.’ The world is characterized by opposites.
  • ‘God’ is logos, meaning reason. There must be a kind of ‘universal reason’ guiding everything that happens in nature.

Empedocles (Sicily, c. 490 – 430 B.C.)

  • Nature consisted of four elements, or ‘roots’. These were earth, air, fire, and water. All things were a mixture of these four but in varying proportions.
  • There are two different that there were two different forces at work in nature. He called them love and strife. Love binds things together, and strife separates them.

Anaxagoras (Athens, 500 – 428 B.C.)

  • The whole exists in each tiny part. So there is ‘something of everything’ in every single cell. He called these minuscule particles which have something of everything in them seeds.
  • He also imagined ‘order’ as a kind of force, creating animals and humans, flowers and tress. He called this force mind or intelligence (nous).
  • He said that the sun was not a god but a red-hot stone, bigger than the Peloponnesian peninsula.
  •  He was very interested in astronomy. He believed that all heavenly bodies were made of the same substance as Earth. He reached this conclusion after studying a meteorite. This gave him the idea that there could be human life on other planets. He also pointed out that the Moon has no light of its own — it’s light comes from Earth, he said.

Democritus (Abdera, c. 460 – 370 B.C.)

  • Everything was built up of tiny invisible blocks, each of which was eternal and immutable. He called these smallest units atoms. Nature’s blocks had to be eternal — because nothing can come from nothing. He believed that nature consisted of an unlimited number and variety of atoms. And precisely because they were so different they could join together into all kinds of different bodies.
  • The atom theory also explains our sense perception. When we sense something it is due to the movement of atoms in space.
  • He believed that the soul was made up of special round, smooth ‘soul atoms’. When a human being died, the soul atoms flew in all directions, and could then become part of a new soul formation.