Publicola (4.1-4.2)

When, accordingly, the youths had been persuaded and held conference with the Aquillii, it was decided that all the conspirators should swear a great and dreadful oath, pouring in libation the blood of a slain man, and touching his entrails. For this purpose they met at the house of the Aquillii.[*] Now the room in which the ceremony was to be held was, as was natural, dark and somewhat desolate. Without their knowing it, therefore, a slave named Vindicius had concealed himself therein, not with design, or with any inkling of what was to happen there;

he merely chanced to be there, and when they came in with anxious haste, he was afraid to be seen by them, and hid himself behind a chest that lay there, so that he saw what they did, and heard what they resolved upon. Their decision was to kill the consuls, and when they had written letters to Tarquin to this effect, they gave them to his envoys, who were living there as guests of the Aquillii, and were then present at the conspiracy.