V. The use of reason is the first requisite to constitute the obligation of a promise, which ideots, madmen, and infants are consequently incapable of making. The case of minors is somewhat different. For although they may not have a sound judgment, yet it is not a permanent defect, nor sufficient of itself to invalidate all their acts. It cannot be certainly defined at what period of life reason commences. But it must be judged of from daily actions, or from the particular customs of each country. Amongst the Hebrews a promise made by a male at the age of thirteen, and by a female at the age of twelve, was valid. In other nations, the civil laws, acting upon just motives, declare certain promises made by wards and minors to be void, not only among the Romans, but among the Greeks also, as it has been observed by Dion Chrysostom in his twenty-fifth oration. To do away the effect of improvident promises, some laws introduce actions of recovery, or restitution. But such regulations are peculiar to the civil law, and have no immediate connection with the law of nature and of nations, any farther than that wherever they are established, it is consonant to natural justice that they should be observed. Wherefore if a foreigner enter into an agreement with a citizen or subject of any other country; he will be bound by the laws of that country, to which, during his residence therein, he owes a temporary obedience. But the case is different, where an agreement is made upon the open sea, or in a desert island, or by letters of correspondence. For such contracts are regulated by the law of nature alone, in the same manner as compacts made by sovereigns in their public capacity. VI. The consideration of promises, made under an error, is a subject of some intricacy. For it, in general, makes a difference, whether the promiser knew the full extent of his promise, and the value of the thing promised, or not, or whether the contract, which was made, originated in fraudulent intention, or not, or whether one of the parties was privy to the fraud; and whether the fulfilment of it was an act of strict justice, or only of good faith. For according to the variety of these circumstances, writers pronounce some acts void and others valid, leaving the injured party a discretionary power to rescind or amend them.