It may be understood, therefore, of what importance it was to obtain the services of a Cicero, or of a Hortensius, who was unrivalled at the Roman bar when Cicero began to plead.
There were three special modes of oratory in which Cicero displayed his powers.

He spoke either before the judges--a large body of judges who sat collected round the Praetor, as in the case of Sextus Roscius--or in cases of civil law before a single judge, selected by the Praetor, who sat with an assessor, as in the case of Roscius the actor, which shall be mentioned just now.

This was the recognized work of his life, in which he was engaged, at any rate, in his earlier years; or he spoke to the populace, in what was called the Concio, or assembly of the people--speeches made before a crowd called together for a special purpose, as were the second and third orations against Catiline; or in the Senate, in which a political rather than a judicial sentence was sought from the votes of the Senators.

There was a fourth mode of address, which in the days of the Emperors became common, when the advocate spoke "ad Principem;" that is, to the Emperor himself, or to some ruler acting for him as sole judge.

It was thus that Cicero pleaded before Caesar for Ligarius and for King Deiotarus, in the latter years of his life.