Prayer to Mars

A single sentence Cato adds immediately after the great prayer to Mars (cato-mars-lustratio-001): what to do if the rite has gone wrong.

"If you have not been satisfied by that pig, I make atonement with this pig." That is, for the case where the offering is not accepted, a second is provided which covers the first.

The whole mechanics of Roman ritual is visible here. Correctness matters more than sincerity: if something has been done wrongly, the error is repaired by a further sacrifice, not by repentance. A rite can be redone the way an improperly executed contract is redone — and Cato provides for it in his handbook alongside the sowing rate.

The word piaculum itself means "that by which something is made good": not a gift but a compensation.