Aristotle: A Treatise on Government

BOOK IV 4. CHAPTER IV (continued)

We have now proved that there are various forms of government and have assigned a reason for it; and shall proceed to show that there are even more than these, and what they are, and why; setting out with the principle we have already laid down. We admit that every city consists not of one, but many parts: thus, if we should endeavour to comprehend the different species of animals we should first of all note those parts which every animal must have, as a certain sensorium, and also what is necessary to acquire and retain food, as a mouth and a belly; besides certain parts to enable it to move from place to place. If, then, these are the only parts of an animal and there are differences between them; namely, in their various sorts of stomachs, bellies, and sensoriums: to which we must add their motive powers; the number of the combinations of all these must necessarily make up the different species of animals. For it is not possible that the same kind of animal should have any very great difference in its mouth or ears; so that when all these are collected, who happen to have these things similar in all, they make up a species of animals of which there are as many as there are of these general combinations of necessary parts.