Plutarch, Sulla
Bernadotte Perrin, Ed.

4. Of course this distressed Marius; but since he considered Sulla to be beneath his envy, he used him in his campaigns, during his second consulship as legate, or lieutenant, and during his third as military tribune, and through his agency performed many successful services. For instance, as legate, Sulla captured Copillus, chieftain of the Tectosages; and as tribune, he persuaded the great and populous nation of the Marsi to become friends and allies of Rome. [2] But perceiving that Marius was vexed with him for these successes, and that he was no longer glad to give him opportunities for action, but opposed his advancement, he attached himself to Catulus, the colleague of Marius in the consulship, a worthy man, but too sluggish for arduous contests. By him he was entrusted with the leading and most important enterprises, and rose to power and fame. [3] He not only subdued in war a large part of the Barbarians of the Alps, but when provisions ran low, he undertook the task of furnishing them, and made them so abundant that the soldiers of Catulus lived in plenty, and had some to spare for those of Marius. At this, as Sulla himself says,¹ Marius was greatly distressed. [4] So slight and puerile were the first foundations and occasions of that hatred between them, which afterwards led them through civil bloodshed and irreparable discords to tyranny and the confusion of the whole state. This proved that Euripides was a wise man, and acquainted with the distempers of civil government, when he exhorted men to beware of ambition as a deity most injurious and fatal to its votaries.²