Diogenes Laertius: Lives of Eminent Philosophers, Vol. 2 (Loeb)

...however, he decided against it after seeing how many people had arrived from those cities.

Later, he became a student of Socrates and benefited so much that he advised his own disciples to become fellow-students with him under Socrates. Living in the Peiraeus, he would walk the forty stadia About five miles. every day to hear Socrates. From him, he learned endurance and cultivated a lack of emotion, thereby becoming the first to initiate the practice of Cynicism. He maintained that hard work is a virtue, using the examples of the great Heracles and Cyrus—the former representing the Greeks, the latter the barbarians.

3 He was the first to define a "statement," saying: "A statement is that which sets forth what a thing was or is." He would often say, "I would rather go mad than feel pleasure," and "One ought to associate only with women who will be grateful for it." When a youth from Pontus was about to attend his lectures and asked what he needed, he replied, "A new notebook, a new pen, and a new tablet," implying the need for a new mind as well. Original: "βιβλιαρίου καινοῦ καὶ γραφείου καινοῦ καὶ πινακιδίου καινοῦ," playing on the Greek word kai nou (and a mind). To one who asked what kind of woman he should marry, he said, "If she is beautiful, you will share her with others; if she is ugly, she will be a punishment for you." Once, having heard that Plato was speaking ill of him, he said, "It is a royal privilege to do good and be spoken of ill." Original: "βασιλικόν," ἔφη, "καλῶς ποιοῦντα κακῶς ἀκούειν."

4 Once, while being initiated into the Orphic mysteries, the priest told him that those who were initiated would enjoy many good things in Hades. "Why then," Antisthenes asked, "do you not die?"