means of redress to the person injured, it must take care that a spirit of revenge does not turn this fair demand into a pretext for injustice. This seems the more necessary when we reflect, first, that in a state of nature the person originally committing the wrong would resist him who sought satisfaction, should he trespass the confines of right in his eagerness for revenge; whereas here, the irresistible authority of the State comes in to check further retaliation; and secondly, that general definitions (which are always necessary when a third is to decide) invariably tend to encourage the pretext before-mentioned. The imprisonment of debtors therefore might seem to require still further exceptions, as the greater number of laws relating to them allow.
Actions which are undertaken by mutual agreement are exactly similar to those which a man performs of himself, without immediate reference to others, and I have only to repeat of them what I have already observed of the latter. There is one class of such actions, however, which requires wholly special regulations; I mean those which are not concluded at once, but extend in their operation to the future. Under this head come promises or engagements which impose perfect duties on the parties to the engagement, whether it be mutual or not. By these, portions of property are made over from one person to another: and if the party transferring it retracts from his engagement by trying to recover what has been transferred, security is disturbed. It is therefore one of the most important duties pertaining to the State to see that such engagements are binding. But the restraint which every engagement imposes is then only just and salutary, when, firstly, the implied limitation extends to him alone who enters into it; and secondly, when he has in general, and at the time of the engagement, acted with a proper capacity of reflection,
