It is possible, however, to detect more subtle effects in the relations between chorus and actors. Since the chorus is usually friendly to the principal character, the bond of sympathy is often strengthened by having the chorus of the same sex and of about the same age as that character. So, in Aeschylus’ _Libation-Bearers_ the choreutae are Trojan slave women who are cognizant of conditions in the palace and fully share Electra’s eagerness to avenge her father’s murder. In Sophocles’ _Maidens of Trachis_ the chorus of girls is in thorough accord with the gentle, unsophisticated Deianira. Furthermore, men or older women might have warned her against sending to her husband a robe dipped in the centaur’s blood, an act which is so essential to the plot; but such innocence is made to seem entirely plausible by reason of the youth and inexperience of the chorus. On the contrary, sometimes the run of the plot requires an effect precisely the opposite. In Sophocles’ _Antigone_, for example, the isolation of the heroine is intensified by a chorus, not only of men but of old men, who would be least sympathetic with her violation of a public edict. In Aeschylus’ _Prometheus Bound_ the defiant Titan would have scorned the overtures of a group of men, whoever they might be, but the feminine tact and sympathy of the Oceanides reach his heart at once. Such a chorus, moreover, is an effective foil the better to emphasize the hero’s indomitable strength and will-power. In Aeschylus’ _Persians_ the chorus of Persian elders is not only natural in itself, but such experienced men’s fear for the army and their grief at its misfortunes produce an impression of utter collapse beyond the power of any chorus of women to effect. In Aristophanes’ _Knights_ the chorus, in spite of criticisms, was appropriately constituted, since it represented a body of men who are said to have entertained a special grudge against Cleon. It would be easy to extend this topic to a great length. Suffice it to state that both the extant plays and the ancient commentaries upon them[246] prove that the Greek poets expended no little thought upon this detail of their dramaturgy.