But the friendship whose motive is utility is fruitful in accusations; for as the friends here use each other solely with a view to their own advantage, each always wants the larger share and thinks he has less than his due, and reproaches the other with not doing for him so much as he requires and deserves; though, in truth, it is impossible for the one who is doing a service to supply all that the other wants.

But it seems that as the rules of justice are twofold, the unwritten and those that are set down in laws, so the friendship whose motive is utility is of two kinds⁠—one resting on disposition, the other on contract. And accusations are most apt to arise when the relation is understood in one sense at the commencement, and in the other sense at the conclusion.

That which rests on contract is that in which there are specified conditions, and it is of two kinds: one is purely commercial, on the principle of cash payments; the other is less exacting in point of time, though in it also there is a specified quid pro quo.