WHAT OF THE DIFFERENCES OF RATIONALITY, IF THE SOUL BE ONE?
If, however, the Soul be one, why is some one soul reasonable, another irrational, or some other one merely vegetative? The indivisible part of the soul consists in reason, which is not divided in the bodies, while the part of the divisible soul in the bodies (which, though being one in herself, nevertheless divides herself in the bodies, because she sheds sentiment everywhere), must be regarded as another power of the soul (the sensitive power); likewise, the part which fashions and produces the bodies is still another power (the vegetative power); nevertheless, this plurality of powers does not destroy the unity of the soul. For instance, in a grain of seed there are also several powers; nevertheless this grain of seed is one, and from this unity is born a multiplicity which forms a unity.