4 A stipulation is conditional, when performance is made to depend on some uncertain event in the future, so that it becomes actionable only on something being done or omitted: for instance, 'Do you promise to give five aurei if Titius is made consul?' If, however, a man stipulates in the form 'Do you promise to give so and so, if I do not go up to the Capitol?' the effect is the same as if he had stipulated for payment to himself at the time of his death. The immediate effect of a conditional stipulation is not a debt, but merely the expectation that at some time there will be a debt: and this expectation devolves on the stipulator's heir, supposing he dies himself before fulfilment of the condition. 5 It is usual in stipulations to name a place for payment; for instance, 'Do you promise to give at Carthage?' Such a stipulation as this, though in its terms absolute, implies a condition that enough time shall be allowed to the promisor to enable him to pay the money at Carthage. Accordingly, if a man at Rome stipulates thus, 'Do you promise to pay today at Carthage?' the stipulation is void, because the performance of the act to be promised is a physical impossibility. 6 Conditions relating to past or present time either make the obligation void at once, or have no suspensive operation whatever. Thus, in the stipulation 'Do you promise to give so and so, if Titius has been consul, or if Maevius is alive?' the promise is void, if the condition is not satisfied; while if it is, it is binding at once: for events which in themselves are certain do not suspend the binding force of an obligation, however uncertain we ourselves may be about them. 7 The performance or nonperformance of an act may be the object of a stipulation no less than the delivery of property, though where this is the case, it will be best to connect the nonperformance of the act to be performed, or the performance of the act to be omitted, with a pecuniary penalty to be paid in default, lest there be doubt as to the value of the act or omission, which will make it necessary for the plaintiff to prove to what damages he is entitled. Thus, if it be a performance which is stipulated for, some such penalty should be added as in the following: 'If so and so is not done, do you promise to pay ten aurei as a penalty?' And if the performance of some acts, and the nonperformance of others, are bargained for in the same stipulation, a clause of the following kind should be added, 'If any default is made, either as contrary to what is agreed upon, or by way of nonperformance, do you promise to pay a penalty of ten aurei?' TITLE XVI. OF STIPULATIONS IN WHICH THERE ARE TWO CREDITORS OR TWO DEBTORS