8 A lunatic cannot enter into any contract at all, because he does not understand what he is doing.
9 On the other hand a pupil can enter into any contract, provided that he has his guardian's authority, when necessary, as it is for incurring an obligation, though not for imposing an obligation on another person.
10 This concession of legal capacity of disposition is manifestly reasonable in respect of children who have acquired to some understanding, for children below the age of seven years, or who have just passed that age, resemble lunatics in want of intelligence. Those, however, who have just completed their seventh year are permitted, by a beneficent interpretation of the law, in order to promote their interests, to have the same capacity as those approaching the age of puberty; but a child below the latter age, who is in paternal power, cannot bind himself even with his father's sanction.
11 An impossible condition is one which, according to the course of nature, cannot be fulfilled, as, for instance, if one says: 'Do you promise to give if I. touch the sky with my finger?' But if the stipulation runs: 'Do you promise to give if I do not touch the sky with my finger?' it is considered unconditional, and accordingly can be sued upon at once.
12 Again, a verbal obligation made between persons who are not present with one another is void. This rule, however, afforded contentious persons opportunities of litigation, by alleging, after some interval, that they, or their adversaries, had not been present on the occasion in question; and we have therefore issued a constitution, addressed to the advocates of Caesarea, in order with the more dispatch to settle such disputes, whereby it is enacted that written documents in evidence of a contract which recite the presence of the parties shall be taken to be indisputable proof of the fact, unless the person, who resorts to allegations usually so disgraceful, proves by the clearest evidence, either documentary or borne by credible witnesses, that he or his adversary was elsewhere than alleged during the whole day on which the document is stated to have been executed.
13 Formerly, a man could not stipulate that a thing should be conveyed to him after his own death, or after that of the promisor; nor could one person who was in another's power even stipulate for conveyance after that person's death, because he was deemed to speak with the voice of his parent or master; and stipulations for conveyance the day before the promisee's or promisor's decease were also void. Stipulation, however, as has already been remarked, derive their validity from the consent of the contracting parties, and we therefore introduced a necessary emendation in respect also of this rule of law, by providing that a stipulation shall be good which bargains for performance either after the death, or the day before the death, of either promisee or promisor.
14 Again, a stipulation in the form: 'Do you promise to give today, if such or such a ship arrives from Asia tomorrow?' was formerly void, as being preposterous in its expression, because what should come last is put first. Leo, however, of famous memory held that a preposterous stipulation in the settlement of a dowry ought not to be rejected as void, and we have determined to allow it perfect validity in every case, and not merely in that in which it was formerly sanctioned.
15 A stipulation, say by Titius, in the form: 'Do you promise to give when I shall die' or 'when you shall die'? is good now, as indeed it always was even under the older law.
16 So too a stipulation for performance after the death of a third person is good.
17 If a document in evidence of a contract states that so and so promised, the promise is deemed to have been given in answer to a preceding question.