Summa contra Gentiles2.64 Chapter LXIV. That the soul is not a harmony

Not unlike the foregoing opinion is the view of those who say that the soul is a harmony. For they meant that the soul is a harmony not of sound, but of contraries, whereof they observed animate bodies to be composed. In the De Anima this opinion is apparently set down to Empedocles: Gregory of Nyssa ascribes it to Dinarchus: and it is to be refuted in the same way as the foregoing opinion, as well as by arguments proper to itself.

For every mixed body has harmony and temperament. Nor can harmony move a body, nor rule it, nor curb the passions, any more than temperament can do so. Again, it is subject to intension and remission, like temperament. All of which show that the soul is neither harmony nor temperament.

Again. The notion of harmony applies more to the qualities of the body than to those of the soul: for health is harmony of the humours; strength, of sinews and bones;

beauty, of limbs and colours. Whereas it cannot be said of what things sense or intellect or other parts of the soul are the harmony. Therefore the soul is not a harmony.

Moreover. Harmony is taken in two senses. In one way, for the composition itself, in another for the manner of composition. Now the soul is not a composition: because each part of the soul would have to be the composition of some of the parts of the body,- and this cannot be verified. Likewise, it is not the manner of a composition: because, since in the various parts of the body there are various manners or proportions of composition, each part of the body would have a distinct soul, for bone, flesh, and sinew would have different souls, since they are composed in different proportions: which is clearly false. Therefore the soul is not a harmony.