was defined to be the knowledge of how to speak well in expository
discourses and dialectic as the knowledge of how to argue rightly in
matters of question and answer. Both rhetoric and dialectic were
spoken of by the Stoics as virtues for they divided virtue in its
most generic sense in the same way as they divided philosophy into
physical, ethical, and logical. Rhetoric and dialectic were thus the
two species of logical virtue. Zeno expressed their difference by
comparing rhetoric to the palm and dialectic to the fist.

Instead of throwing in poetic and grammar with rhetoric, the Stoics
subdivided dialectic into the part which dealt with the meaning and
the part which dealt with the sound, or as Chrysippus phrased it,
concerning significants and significates. Under the former came the
treatment of the alphabet, of the parts of speech, of solecism, of
barbarism, of poems, of amphibolies, of metre and music--a list which
seems at first sight a little mixed, but in which we can recognise
the general features of grammar, with its departments of phonology,
accidence, and prosody. The treatment of solecism and barbarism in
grammar corresponded to that of fallacies in logic. With regard to
the alphabet it is worth noting that the Stoics recognised seven
vowels and six mutes. This is more correct than our way of talking of
nine mutes, since the aspirate consonants are plainly not mute. There
were, according to the Stoics, five parts of speech--name,
appellative, verb, conjunction, article. 'Name' meant a proper name,
and 'appellative' a common term.

There were reckoned to be five virtues of speech--Hellenism,
clearness, conciseness, propriety, distinction. By 'Hellenism' was
meant speaking good Greek. 'Distinction' was defined to be 'a diction
which avoided homeliness.' Over against these there were two