Of men's acts

Of the acts of men which are advantageous to other men, some are simple, others of a mixed character.

The kinds of simple acts

Some simple acts are merely kind, others are reciprocal. The kindnesses either are unmixed or involve a kind of mutual obligation. Unmixed kindnesses are either fulfilled in the present, or are directed to the future. A useful deed is accomplished in the present; and in regard to this, it is not necessary to speak. [W]hile it is advantageous, to be sure, it has no legal effect. Of the same character is a donation by which ownership of property is transferred, and that topic we treated above, when the matter of acquiring ownership was under consideration. Not only promises to give but also promises to perform are directed toward the future; these also we have already treated.

Advantageous acts which involve a mutual obligation are those which dispose of property without alienation, or accomplish a deed in such a way that some effect remains. Such in regard to things is the permission to use, which is called a gratuitous bailment; and in regard to deeds the undertaking of a costly service, or one implying obligations, which is called a mandate; one form of the mandate is the deposit in trust, which involves the expenditure of labour in guarding and keeping a thing.