Isaeus studied under Isocrates, and it is therefore reasonable to follow the chronological order and take the master first; but as the master survived the pupil by several years, and was actively engaged in literature down to the day of his death, ordinary considerations of seniority do not apply in this case. It is more satisfactory to study Isaeus in relation, not to Isocrates, but to the earlier speech-writers, Antiphon and Lysias. He is more closely connected with them in his subject-matter, since he is, like them, essentially a practical writer, and his businesslike style has more affinity to the terse condensation of Lysias than to the florid ‘epideictic’ diction of the author of the _Panegyric_. In language there is not very much difference between Lysias and Isaeus; both use the current vocabulary, making a literary medium out of the popular speech of their day. A search through the latter’s speeches re-discovers a certain number of words which, so far as our knowledge goes, have a poetical tinge; but practically all these may be found in other orators and prose-writers.[159] Again, there are a few noteworthy metaphors, such as ἐκκόπτειν, to ‘knock out’ or ‘knock on the head’—this is used again by Dinarchus—and καθιπποτροφεῖν, ‘to race away one’s money,’ _i.e._ squander it on a stable. We know little of the idioms of the language spoken in the streets of Athens in the fourth century, but we do know that popular speech has always a tendency to the employment of rough metaphors, and where we come into contact with the spoken word we expect to find expressions of this kind.[160] A study of the private letters contained among the Oxyrhynchus Papyri will give many examples to the point.[161] Lastly, a few words recall the language of comedy.[162] We may readily believe that, in admitting these few blemishes to the purity of his Atticism, the orator was indulging in a realism of which we find very few traces, as a rule, in literary prose.[163] His grammar, according to strict Attic rule, is occasionally at fault,[164] and the MSS. exhibit a certain number of word-forms which are supposed to be un-Attic.[165] Whether we should emend these passages to suit the supposed standard, or make the standard more liberal to admit such passages, is a matter for controversy. The MSS. of Thucydides exhibit a wealth of ingenious perversity in the way of grammar, and in that case, though many critics have spent their ingenuity on reducing the text to order and decency, an opposite school of criticism maintains that the historian may have chosen to write as he liked. The greatest artists are above the laws of their art, and Isaeus may have condescended to a level which he knew not to be the highest.