I shall not annoy the rest of you while complying with his
request. Annoy me, said I, who asked you? Quintus and Pomponius also said
that they entertained the same wish; so he began. And I beg of you,
Brutus, to consider whether what he said appears to you to sufficiently
embrace the doctrines of Antiochus, which I know you, who were a constant
attendant on the lectures of his brother Aristus, approve of highly. Thus
he spoke:--

IV. What great elegance there is in the Peripatetic system I have
explained a little time ago, as briefly as I could. But the form of the
system, as is the case with most of the other schools, is threefold: one
division being that of nature; the second, that of arguing; the third,
that of living. Nature has been investigated by them so thoroughly that
there is no part of heaven, or earth, or sea (to speak like a poet), which
they have passed over. Moreover, after having treated of the origin of
things, and of the universal world, so as to prove many points not only by
probable arguments, but even by the inscrutable demonstrations of
mathematicians, they brought from the subjects which they had investigated
abundant materials to assist in attaining to the knowledge of secret
things. Aristotle investigated the birth, and way of living, and figure of
every animal; Theophrastus examined the causes, and principles, and
natures of plants, and of almost everything which is produced out of the
earth; by which knowledge the investigation of the most secret things is
rendered easier. Also, they have given rules for arguing, not only
logically, but oratorically; and a system of speaking in both these
manners, on every subject, has been laid down by Aristotle, their chief;
so that he did not always argue against everything, as Arcesilas did; and
yet he furnished one on every subject with arguments to be used on both
sides of it.

But, as the third division was occupied about the rules of living well, it
was also brought back by those same people, not only to the system of
private life, but also to the direction of affairs of state. For from
Aristotle we have acquired a knowledge of the manners, and customs, and
institutions of almost every state, not of Greece only, but also of the
Barbarians; and from Theophrastus we have learnt even their laws: and each
of them taught what sort of man a leader in a state ought to be, and also
wrote at great length to explain what was the best constitution for a
state.