At this time there was a bitter rivalry between the Senate and the
equestrian order, or commercial class. From the former were chosen the
governors of the provinces, from the latter came the tax-gatherers
(_publicani_) and the money-brokers (_negotiatores_). It will
help us to understand better the condition of affairs, if we study the
composition of the Senate and the Equites.

The Senators, three hundred in number (later their number was
increased to six hundred), held their office for life. When vacancies
occurred from death, or occasionally from removal, they were filled by
the Censor, [Footnote: See the duties of Censor] who appointed a
person that had held one of the following offices: Dictator, Consul,
Praetor, Curule Aedile, or, after the time of Sulla, Quaestor. All
persons who had held these offices, or that of Tribune, were allowed
to join in debate in the Senate, but not to vote. No Senator could
engage in business. Hence he must be wealthy.

We saw in Chapter IV. that Roman citizens were divided into six
classes according to their property, and that these classes were
subdivided into one hundred and ninety-three other classes called
centuries. About 225, the number was increased to three hundred and
seventy-three. Eighteen of the centuries of the first class were
called EQUITES, and must have property worth twenty thousand dollars
or more. This name was given to them because at first they served in
the army as horsemen, though in later times the cavalry was composed
only of allied troops. The Equites were originally from the
aristocracy alone, but, as the plebeians increased in wealth, many of
them became rich enough to be included in this class.

There was no hostility between the Senate and the Equites until, in