One of three Athenian brothers who took a part in the expedition that Theseus made to the land of the Amazons. The other brothers were called Euneus and Thoas. Solois fell in love with Antiope unbeknown to the rest, and revealed his secret to one of his intimate friends. That friend made overtures to Antiope, who positively repulsed the attempt upon her, but treated the matter with discretion and gentleness, and made no denunciation to Theseus. Then Solois, in despair, threw himself into a river and drowned himself. When Theseus learned the fate of the young man, and what had caused it, he recalled a certain oracle which he had once received at Delphi. For it had there been enjoined upon him by the Pythian priestess that when, in a strange land, he should be sorest vexed and full of sorrow, he should found a city there, and leave some of his followers to govern it. For this cause he founded a city there, and called it, from the Pythian god, Pythopolis, and the adjacent river, Solois, in honor of the young man. And he left there the brothers of Solois, to be the city's presidents and law-givers, and with them Hermus, one of the noblemen of Athens.
- Plutarch. Theseus, 26.