Book 1
1
We have given only a concise and summary account of those thinkers who have expressed views about the causes and reality, and of their doctrines. Nevertheless we have learned thus much from them: that not one of those who discuss principle or cause has mentioned any other type than those which we we have distinguished in the Physics. Aristot. Phys. 2.3 Clearly it is after these types that they are groping, however uncertainly.
2
Some speak of the first principle as material, whether they regard it as one or several, as corporeal or incorporeal: e.g. Plato speaks of the Great and Small; the ItaliansSee note on Aristot. Met. 5.15. of the Unlimited; Empedocles of Fire, Earth, Water and Air; Anaxagoras of the infinity of homoeomeries.
3
All these have apprehended this type of cause; and all those too who make their first principle air or water or something denser than fire but rarer than airThe various references in Aristotle to material principles intermediate between certain pairs of elements have been generally regarded as applying to Anaximander’s ἄπειρον or Indeterminate; but the references are so vague (cf. Aristot. Met. 7.6, Aristot. Phys.187a 14, 189b 3, 203a 18) that it seems better to connect them with later and minor members of the Milesian school. Cf. Ross’s note ad loc.(for some have so described the primary element). These, then, apprehended this cause only, but others apprehended the source of motion—e.g. all such as make Love and Strife, or Mind, or Desire a first principle.
4
As for the essence or essential nature, nobody has definitely introduced it; but the inventors of the Forms express it most nearly. For they do not conceive of the Forms as the matter of sensible things (and the One as the matter of the Forms), nor as producing the source of motion (for they hold that they are rather the cause of immobility and tranquillity); but they adduce the Forms as the essential nature of all other things, and the One as that of the Forms.
