The relation between the youth and his preceptor was not unlike that of the _contubernium_ in military life, in which the general to whom a lad was committed was supposed to be responsible for his welfare and conduct as well as for his education in the art of war: thus Cicero says of Caelius[294] that at that period of his life no one ever saw him "except with his father or with me, or in the very well-conducted house of M.Crassus" (who shared with Cicero in the guardianship).
"Fuit assiduus mecum," he says a little farther on.

This kind of pupilage was called the _tirocinium fori_, in which a lad should be pursuing his studies for the legal profession, and also his bodily exercises in the Campus Martius, so that he might be ready to serve in the army for the single campaign which was still desirable if not absolutely necessary.

When he had made his first speech in a court of law, he was said _tirocinium ponere_,[295] and if it were a success, he might devote himself more particularly henceforward to the art and practice of oratory.

No doubt all really ambitious young men, who aimed at high office and an eventual provincial government, would, like Caesar, endeavour to qualify themselves for the army as well as the Forum.

Cicero, however, whose instincts were not military, served only in one campaign, at the age of seventeen, and apparently he advised Caelius to do no more than this.