We have now to see how they gained this importance and this power, and what use they made of their capital and their opportunities.

This is not usually explained or illustrated in the ordinary histories of Rome, yet it is impossible without explaining it to understand either the social or the public life of the Rome of this period.
The men of business may be divided into two classes, according as they undertook work for the State or on their own account entirely.

It does not follow that these two classes were mutually exclusive; a man might very well invest his money in both kinds of undertaking, but these two kinds were totally distinct, and called by different names.

A public undertaking was called _publicum_,[109] and the men who undertook it _publicani_; a private undertaking was _negotium_, and all private business men were known as _negotiatores_.

The publicani were always organised in joint-stock companies (_societates publicanorum_); the negotiatores might be in private partnership with one or more partners,[110] but as a rule seem to have been single individuals.