§ VI. On the Effects of Contract

A contract, whether concerning a thing to be given, or concerning a thing to be done or omitted, brings with it the obligation of executing the contract and of repairing damages following from neglect of execution.

I. The obligation of executing the contract; this obligation, since contracts must be regarded as entered into in good faith, extends not only to those things which are expressed in explicit words, but also to those things which equity, usage, or law postulates for the nature of the contract.

What if, in the time which intervenes between the contract entered into and its execution, the value either of money or of things is changed?

Response 1. If there is discussion of ordinary or, so to speak, normal changes, the contract must be put into execution just as it lies, because the contracting parties are judged to have consented to changes of this kind.

Response 2. If there is question of a greater change, this must be said:

1. If law, or an express pact, or custom assigns a norm, one must stand by these. With respect to law or pact the matter is clear; with respect to custom it follows from the fact that the contracting parties are judged to have contracted according to custom.

2. With law, express pact, and custom set aside, the one who suffers damage by executing the contract is bound to undergo this if there is question of a case which could be foreseen or feared; otherwise, if there is discussion of a case which could not be foreseen or feared, as an earthquake. The reason is that every contract entered into in the mode assigned in the question has something of an aleatory contract; and, this being posited, the former cases are judged to be comprehended in the contract, but not the latter. We shall apply these things in their own place to several contracts.

II. The obligation of repairing damages. But in order that this obligation arise from neglect of the contract, there is required either theological fault, or a special pact, or juridical fault together with the sentence of a judge.

These things having been noted concerning the effects of contracts in general, we shall speak specifically about the effects of qualified contracts, namely about the effects of a contract entered into under a condition, under a mode, for a cause, for a day, under a penalty, and confirmed by oath.