Publicola (3.3-3.4)

And it was with this that the envoys busied themselves, making the property merely a pretext for remaining in the city, and saying that they were selling part of it, and reserving part, and sending part of it away. At last they succeeded in corrupting two of the noble families of Rome, that of the Aquillii, which had three senators, and that of the Vitellii, which had two. All these, by the mother’s side, were nephews of Collatinus the consul, and besides, the Vitellii were related in another manner to Brutus.

For Brutus had married a sister of theirs, and she had borne him several sons. Two of these, who had come to manhood, and were their near kindred and close companions, the Vitellii won over and persuaded to join the plot for betraying the city, to ally themselves with the great family and the royal expectations of the Tarquins, and rid themselves of the stupidity and cruelty of their father. For they gave the name of cruelty to that father’s inexorable treatment of criminals, and as for his stupidity, he had for a long time, as it appears, feigned and assumed this, to insure his safety from the cruel designs of the tyrants, and afterwards the surname of Brutus, which had been given him for it, clung to him.