132. Like Empedokles, Anaxagoras required some external cause to produce motion in the mixture. Body, Parmenides had shown, would never move itself, as the Milesians had supposed. Anaxagoras called the cause of motion by the name of Nous. It was this which made Aristotle say that he “stood out like a sober man from the random talkers that had preceded him,”[702] and he has often been credited with the introduction of the spiritual into philosophy. The disappointment expressed both by Plato and Aristotle as to the way in which Anaxagoras worked out the theory should, however, make us pause to reflect before accepting too exalted a view of it. Plato[703] makes Sokrates say: “I once heard a man reading a book, as he said, of Anaxagoras, and saying it was Mind that ordered the world and was the cause of all things. I was delighted to hear of this cause, and I thought he really was right.... But my extravagant expectations were all dashed to the ground when I went on and found that the man made no use of Mind at all. He ascribed no causal power whatever to it in the ordering of things, but to airs, and aethers, and waters, and a host of other strange things.” Aristotle, probably with this passage in mind, says:[704] “Anaxagoras uses Mind as a _deus ex machina_ to account for the formation of the world; and whenever he is at a loss to explain why anything necessarily is, he drags it in. But in other cases he makes anything rather than Mind the cause.” These utterances may well suggest that the Nous of Anaxagoras did not really stand on a higher level than the Love and Strife of Empedokles, and this will only be confirmed when we look at what he himself has to say about it. Footnote 702: Arist. _Met._ Α, 3. 984 b 15 (R. P. 152). Footnote 703: Plato, _Phd._ 97 b 8 (R. P. 155 d). Footnote 704: Arist. _Met._ Α, 4. 985 a 18 (R. P. 155 d). In the first place, Nous is unmixed (fr. 12), and does not, like other things, contain a portion of everything. This would hardly be worth saying of an immaterial mind; no one would suppose that to be hot or cold. The result of its being unmixed is that it “has power over” everything, that is to say, in the language of Anaxagoras, it causes things to move.[705] Herakleitos had said as much of Fire, and Empedokles of Strife. Further, it is the “thinnest” of all things, so that it can penetrate everywhere, and it would be meaningless to say that the immaterial is “thinner” than the material. It is true that Nous also “knows all things”; but so, perhaps, did the Fire of Herakleitos,[706] and certainly the Air of Diogenes.[707] Zeller holds, indeed, that Anaxagoras meant to speak of something incorporeal; but he admits that he did not succeed in doing so,[708] and that is historically the important point. Nous is certainly imagined as occupying space; for we hear of greater and smaller parts of it (fr. 12). Footnote 705: