Ab urbe condita
Titus Livius (Livy)
Livy. History of Rome, Volumes 1-2. Roberts, Canon, Rev, translator. London, New York: J. M. Dent and Sons; E. P. Dutton and Co., 1912.
The two sons of Ancus had always felt most keenly their being deprived of their father's throne through the treachery of their guardian; its occupation by a foreigner who was not even of Italian, much less of Roman descent, increased their indignation, when they saw that not even after the death of Tarquin would the crown revert to them, but would suddenly descend to a slave —that crown which Romulus, the offspring of a god, and himself a god, had worn whilst he was on earth, now to he the possession of a slave - born slave a hundred years later!
They felt that it would be a disgrace to the whole Roman nation, and especially to their house, if, while the male issue of Ancus was still,alive, the sovereignty of Rome should be open not only to foreigners but even to slaves. They determined, therefore, to repel that insult by the sword.