ISAEUS (c. 420 B.C.–C. 350 B.C.), Attic orator, the chrono logical limits of whose extant work fall between the years 390 and 353 B.C., is described in the Plutarchic life as a Chalcidian; by Suidas, whom Dionysius follows, as an Athenian. The accounts have been reconciled by supposing that his family sprang from the settlement (anpouxia) of Athenian citizens among whom the lands of the Chalcidian hippobotai (knights) had been divided about 509 B.C. A connection with Euboea would explain the non-Athenian name Diagoras which is borne by the father of Isaeus, while the latter is said to have been "an Athenian by descent" ('AOnvaios T6 ybios). So far as we know, Isaeus took no part in the public affairs of Athens. "I cannot tell," says Dionysius, "what were the politics of Isaeus—or whether he had any politics at all." Isaeus (who was born probably about 420 B.c.) is believed to have been an early pupil of Isocrates, and he certainly was a student of Lysias. The profession of Isaeus was that of which Antiphon had been the first representative at Athens—that of a Xo-yerypaOos, who composed speeches which his clients were to deliver in the law courts. But, while Antiphon had written such speeches chiefly (as Lysias frequently) for public causes, it was with private causes that Isaeus was almost exclusively concerned.
The most interesting recorded event in the career of Isaeus is his connection with Demosthenes, who attained his civic majority in 366. He had resolved to prosecute his fraudulent guardians, and sought the aid of Isaeus. Plutarch states that Demosthenes "employed Isaeus as his master in rhetoric, though Isocrates was then teaching, either (as some say) because he could not pay Isocrates the prescribed fee of ten minae, or because he preferred the style of Isaeus for his purpose, as being vigorous and astute" (opacrriipLov Kai ravainov). The speeches of Demosthenes against Aphobus and Onetor (363-362 B.c.) afford the best pos sible gauge of the sense and the measure in which he was the disciple of Isaeus ; the intercourse between them can scarcely have been either very close or very long. The date at which Isaeus died can only be conjectured from his work. It may be placed about 35o B.C.
Isaeus has a double claim on the student of Greek literature. He is the first Greek writer who comes before us as a consum mate master of strict forensic controversy. He also holds a most important place in the general development of practical oratory, and therefore in the history of Attic prose. Antiphon marks the beginning of that development, Demosthenes its consummation. Between them stand Lysias and Isaeus. The open, even ostenta tious, art of Antiphon had been austere and rigid. The con cealed art of Lysias had charmed and persuaded by a versatile semblance of natural grace and simplicity. Isaeus brings us to a final stage of transition, in which the gifts distinctive of Lysias were to be fused into a perfect harmony with that masterly art which receives its most powerf al expression in Demosthenes.
Here, then, are the two cardinal points by which the place of Isaeus must be determined. We must consider, first, his relation to Lysias; secondly, his relation to Demosthenes.
With less love of antithesis than Lysias, and with a diction almost equally pure and plain, Isaeus yet habitually conveys the impression of conscious and confident art. Hence he is least effective in adapting his style to those characters in which Lysias peculiarly excelled—the ingenuous youth, the homely and peace loving citizen. On the other hand, his more open and vigorous art does not interfere with his moral persuasiveness where there is scope for reasoned remonstrance, for keen argument or for powerful denunciation. Passing from diction and composition to the treatment of subject-matter, we find the divergence wider still. Lysias usually adheres to a simple four-fold division— proem, narrative, proof, epilogue. Isaeus frequently interweaves the narrative with the proof. He shows the most dexterous ingenuity in adapting his manifold tactics to the case in hand, and often "out-generals" (Karaurparnya) his adversary by some novel and daring disposition of his forces. Lysias, again, usually contents himself with a merely rhetorical or sketchy proof ; Isaeus aims at strict logical demonstration, worked out through all its steps. As Sir William Jones well remarks, Isaeus lays close siege to the understandings of the jury.
What, we must next ask, is the relation of Isaeus to Demos thenes? The Greek critic who had so carefully studied both authors states his own view in broad terms when he declares that "the power of Demosthenes took its seeds and its beginnings from Isaeus" (Dion. Halic. Isaeus 2o). Attic prose expression had been continuously developed as an art ; the true link between Isaeus and Demosthenes is technical, depending on their con tinuity. The composition of Demosthenes resembles that of Isaeus in blending terse and vigorous periods with passages of more lax and fluent ease, as well as in that dramatic vivacity which is given by rhetorical question and similar devices. In the versatile disposition of subject-matter, the divisions of "narra tive" and "proof" being shifted and interwoven according to cir cumstances, Demosthenes has clearly been instructed by the ex ample of Isaeus. Still more plainly and strikingly is this so in regard to the elaboration of systematic proof ; here Demosthenes invites direct and close comparison with Isaeus by his method of drawing out a chain of arguments, or enforcing a proposition by strict legal argument. And, more generally, Demosthenes is the pupil of Isaeus, though here the pupil became even greater than the master, in that faculty of grappling with an adversary's case point by point, in that aptitude for close and strenuous con flict which is expressed by the words