Demosthenes The Funeral Speech 28

[28] Neither were the Aegeidae ignorant that Theseus, the son of Aegeus, for the first time established equality in the State. ¹ They thought it, therefore, a dreadful thing to be false to the principles of that ancestor, and they preferred to be dead rather than through love of life to survive among the Greeks with this equality lost. The Pandionidae had inherited the tradition of Procne and Philomela, the daughters of Pandion, who took vengeance on Tereus for his crime against themselves. ² Therefore they decided that life was not worth living unless they, akin by race, should have proved themselves to possess equal spirit with those women, when confronted by the outrage they saw being committed against Greece.