The combination of these three victims constituted with the Greeks as well as the Romans an expiatory sacrifice.

Priests and attendants followed the procession: when the third round had been accomplished, the magistrate pronounced a prayer and slaughtered the victims.

From this moment all sins were expiated, and neglect of religious duties effaced, and the city was at peace with its gods.
There were two essential features of this ceremony: the first, that no stranger should be present at it; and the second, that no citizen should be absent from it.

In the latter case the whole city might not have been freed from impurity.

The Suovetaurilia was therefore preceded by a census, which was conducted with the greatest care both at Rome and Athens.