Appian of Alexandria Civil Wars 2.16.112

[112] Brutus and Cassius, who had been designated as praetors at the same time, had a controversy with each other as to which of them should be the city praetor, this being the place of highest honor, either because they were really ambitious of the distinction or as a pretence so that they might not seem to have a common understanding with each other. Caesar, who was chosen umpire between them, is reported to have said to his friends that justice seemed to be on the side of Cassius, but that he must nevertheless favor Brutus. He exhibited the same affection and preference for this man in all things. It was even thought that Brutus was his son, as Caesar was the lover of his mother, Servilia (Cato’s sister) at the time of his birth, ¹ for which reason, when he won the victory at Pharsalus, it is said that he gave an immediate order to his officers to save Brutus by all means. Whether Brutus was ungrateful, or ignorant of his mother’s fault, or disbelieved it, or was ashamed of it; whether he was such an ardent lover of liberty that he preferred his country to everything, or whether it was because he was a descendant of that Brutus of the olden time who expelled the kings, he was aroused and shamed to this deed principally by people who secretly affixed to the statues of the elder Brutus and also to the tribunal of Brutus himself such writings as these, Brutus, are you corrupted by bribes. Brutus, are you dead? or would that you were still alive! or, your posterity is unworthy of you, or, you are not the descendant of that Brutus. These and many like incentives fired the young man to a deed like that of his own ancestor.