Demosthenes was born in 384, and came of age in 366. Before attaining his majority he had resolved on the contest with the guardians who had abused their trust. The two orations Against Aphobos belong to 363 B. C.; the two orations Against Onetor to 362. Now, in 366, Isaeos must have been known for upwards of twenty years as a successful writer of forensic speeches, and also as a master of Attic law, especially in the department of claims to property. No one could be better fitted to arm Demosthenes for his first encounter. There is no doubt whatever that Demosthenes had recourse to the aid of Isaeos. Afterwards, when that relative obscurity in which the critics left the elder orator was hardly broken save by this stray gleam from the glory of the younger, friendly biographers naturally welcomed everything that could add brightness to the borrowed ray ¹ . It is due quite as much to Isaeos as to Demosthenes that we should be on our guard against exaggerations. According to one story, Demosthenes, on coming of age, took Isaeos into his house, and studied with him for four years ² . He is further said to have paid Isaeos 10,000 drachms (about £400) on condition that the teacher should withdraw from a school of Rhetoric which he had opened, and should devote himself wholly to his new pupil ³ . ‘It was a close personal relation,’ writes a brilliant historian, ‘into which they entered, an intellectual armed alliance, in order with their united strength to carry on the contest of vengeance which Demosthenes, like the Heroes of ancient mythology, undertook against the desolaters of his paternal home ⁴ .’ It would be agreeable thus to conceive Isaeos,—as a Pylades divided by nothing but, perhaps, thirty-six years from his young partner in the chastisement of a triple Aegisthos. Plutarch, however, says merely that Demosthenes—‘employed Isaeos as his master in Rhetoric, though Isokrates was then teaching, either (as some say) because he could not pay Isokrates the prescribed fee of ten minae; or because he preferred the style of Isaeos for his purpose, as being vigorous and astute’ ( δραστήριον καὶ πανοῦργον) ⁵ . The school of Isaeos is nowhere else mentioned ⁶ , nor is the name of any other pupil recorded.

The Sixth Oration, On the Estate of Philoktemon (364—363 B. C.), falls in the midst of those years (366—362) which the tradition supposes Isaeos to have reserved for Demosthenes; showing that, if Isaeos had no other disciples, he had at least concurrent occupations. Then another version claims for Isaeos the credit of having taught Demosthenes gratis ⁷ . But the decisive argument is furnished by the speeches Against Aphobos and Onetor. These are not the compositions of one who had given himself wholly to the guidance of Isaeos, who was sitting at the master's feet, who was working under the master's eye. On the contrary, these earliest speeches of Demosthenes have a stamp of their own as marked as it is original. Some valuable hints Demosthenes unquestionably got from Isaeos, and an attempt will be made presently to show what these were. But the limits of the influence forbid us to think that the intercourse between Isaeos and Demosthenes as teacher and learner can have been either very intimate or of very long duration ⁸ .