For, in proportion as the body is capable of being affected in a greater variety of ways, and of affecting external bodies in a great number of ways, so much the more is the mind capable of thinking (IV.xxxviii., xxxix.).

But there seem to be very few things of this kind in nature; wherefore for the due nourishment of the body we must use many foods of diverse nature.
For the human body is composed of very many parts of different nature, which stand in continual need of varied nourishment, so that the whole body may be equally capable of doing everything that can follow from its own nature, and consequently that the mind also may be equally capable of forming many perceptions.
XXVIII.

Now for providing these nourishments the strength of each individual would hardly suffice, if men did not lend one another mutual aid.

But money has furnished us with a token for everything: hence it is with the notion of money, that the mind of the multitude is chiefly engrossed: nay, it can hardly conceive any kind of pleasure, which is not accompanied with the idea of money as cause.
XXIX.

This result is the fault only of those, who seek money, not from poverty or to supply their necessary wants, but because they have learned the arts of gain, wherewith they bring themselves to great splendour.