only in one campaign, at the age of seventeen, and apparently he advised Caelius to do no more than this. Caelius served under Q. Pompeius proconsul of Africa, to whom he was attached as _contubernalis_, choosing this province because his father had estates there.[296] It was only on his return with a good character from Pompeius that he proceeded to exhibit his skill as an orator by accusing some distinguished person--in this case the Antonius who was afterwards consul with Cicero.[297] To attain the skill in oratory which would enable the pupil to make a successful appearance in the Forum, he must have gone through an elaborate training in the art of rhetoric. Cicero does not tell us whether he himself gave Caelius lessons in rhetoric, or whether he sent him to a professional teacher; he had himself written a treatise on a part of the subject--the _de Inventione_ of 80 B.C., the earliest of all his prose works--and was therefore quite able to give the necessary instruction if he found time to do so. It is not the object of this chapter to explain the meaning of rhetoric as the Graeco-Roman world then understood it, or the theory of a rhetorical education; for this the reader must be referred to Professor Wilkins' little book,[298] or, better still, to the main source of our knowledge, the _Institutio Oratoris_ of Quintilian. Something may, however, be said here of the view taken of a rhetorical training by Cicero himself, very clearly expressed in the exordium of the treatise just mentioned, and often more or less directly reiterated in his later and more mature works on oratory. "After much meditation," he says, "I have been led to the conclusion that wisdom without eloquence is of little use to a state, while eloquence without wisdom is often positively harmful, and never of any value. Thus if a man, abandoning the study of reason and duty, which is always perfectly straight and honourable, spends his whole time in the practice of speaking, he is being brought up to be a hindrance to his own development, and a dangerous citizen." This reminds us of Cato's saying that an orator is "vir bonus dicendi peritus." Less strongly expressed, the same view is also found in the exordium of another and more mature treatise on rhetoric, by an author whose name is unknown, written a year or two before that of Cicero: "Non enim parum in se fructus habet copia dicendi et commoditas orationis, si recta intelligentia et definita animi moderatione gubernetur."[299] We may assume that in Cicero's early years the best men felt that the rhetorical art, if it were to be of real value to the individual and the state, must be used with discretion, and accompanied by high aims and upright conduct.