Chapter — Sabetti-Barrett, Compendium of Moral Theology
Chapter IV. On the Modifications of Contracts
496.
By the name of modifications are designated certain clauses added beyond the nature and essence of contracts, so that they now strengthen the obligation of the same contracts, now also increase or determine it, now suspend or destroy it. Moreover, the principal modifications of contracts are: 1st, oath; 2nd, modes; 3rd, conditions. These three must be treated briefly.