Thales: everything is made of water
Anaximenes: the fundamental substance is air
Pythagoras: all things are numbers
Xenophanes: all things are made of earth and water
Heraclitus: fire is the fundamental substance
Heraclitus: everything changes
Parmenides: nothing changes
Empedocles: all change is governed by chance and necessity
Anaxagoras: mind as the primary cause of physical changes
Democritus: cause and effect (mechanism)
