Plutarch, Themistocles
Bernadotte Perrin, Ed.

Speedily, however, as it seems, and while he was still in all the ardor of youth, public affairs laid their grasp upon Themistocles, and his impulse to win reputation got strong mastery over him. Wherefore, from the very beginning, in his desire to be first, he boldly encountered the enmity of men who had power and were already first in the city, especially that of Aristides the son of Lysimachus, who was always his opponent. And yet it is thought that his enmity with this man had an altogether puerile beginning. They were both lovers of the beautiful Stesilaus, a native of Ceos, as Ariston the philosopher has recorded, and thenceforward they continued to be rivals in public life also. [2] However, the dissimilarity in their lives and characters is likely to have increased their variance. Aristides was gentle by nature, and a conservative in character. He engaged in public life, not to win favour or reputation, but to secure the best results consistent with safety and righteousness, and so he was compelled, since Themistocles stirred the people up to many novel enterprises and introduced great innovations, to oppose him often, and to take a firm stand against his increasing influence. [3]

It is said, indeed, that Themistocles was so carried away by his desire for reputation, and such an ambitious lover of great deeds, that though he was still a young man when the battle with the Barbarians at Marathon¹ was fought and the generalship of Miltiades was in everybody's mouth, he was seen thereafter to be wrapped in his own thoughts for the most part, and was sleepless o' nights, and refused invitations to his customary drinking parties, [4] and said to those who put wondering questions to him concerning his change of life that the trophy of Miltiades would not suffer him to sleep. Now the rest of his countrymen thought that the defeat of the Barbarians at Marathon was the end of the war; but Themistocles thought it to be only the beginning of greater contests, and for these he anointed himself, as it were, to be the champion of all Hellas, and put his city into training, because, while it was yet afar off, he expected the evil that was to come.