Plutarch, Theseus
Bernadotte Perrin, Ed.

During the rest of the time, then, Aethra kept his true birth concealed from Theseus, and a report was spread abroad by Pittheus that he was begotten by Poseidon. For Poseidon is highly honored by the people of Troezen, and he is the patron god of their city; to him they offer first fruits in sacrifice, and they have his trident as an emblem on their coinage. [2] But when, in his young manhood, Theseus displayed, along with his vigor of body, prowess also, and a firm spirit united with intelligence and sagacity, then Aethra brought him to the rock, told him the truth about his birth, and bade him take away his fathers tokens and go by sea to Athens. [3] Theseus put his shoulder to the rock and easily raised it up, but he refused to make his journey by sea, although safety lay in that course, and his grandfather and his mother begged him to take it. For it was difficult to make the journey to Athens by land, since no part of it was clear nor yet without peril from robbers and miscreants. [4]

For verily that age produced men who, in work of hand and speed of foot and vigor of body, were extraordinary and indefatigable, but they applied their powers to nothing that was fitting or useful. Nay rather, they exulted in monstrous insolence, and reaped from their strength a harvest of cruelty and bitterness, mastering and forcing and destroying everything that came in their path. And as for reverence and righteousness, justice and humanity, they thought that most men praised these qualities for lack of courage to do wrong and for fear of being wronged, and considered them no concern of men who were strong enough to get the upper hand. [5] Some of these creatures Heracles cut off and destroyed as he went about, but some escaped his notice as he passed by, crouching down and shrinking back, and were overlooked in their abjectness. And when Heracles met with calamity and, after the slaying of Iphitus, removed into Lydia and for a long time did slave's service there in the house of Omphale, then Lydia indeed obtained great peace and security; but in the regions of Hellas the old villainies burst forth and broke out anew, there being none to rebuke and none to restrain them. [6]

The journey was therefore a perilous one for travellers by land from Peloponnesus to Athens, and Pittheus, by describing each of the miscreants at length, what sort of a monster he was, and what deeds he wrought upon strangers, tried to persuade Theseus to make his journey by sea. But he, as it would seem, had long since been secretly fired by the glorious valor of Heracles, and made the greatest account of that hero, and was a most eager listener to those who told what manner of man he was, and above all to those who had seen him and been present at some deed or speech of his. [7] And it is altogether plain that he then experienced what Themistocles many generations afterwards experienced, when he said that he could not sleep for the trophy of Miltiades.¹ In like manner Theseus admired the valor of Heracles, until by night his dreams were of the hero's achievements, and by day his ardor led him along and spurred him on in his purpose to achieve the like.