24 A promise made for an illegal or immoral purpose, as, for instance, to commit a sacrilege or homicide, is void. 25 If a man stipulates for performance on the fulfilment of a condition, and dies before such fulfilment, his heir can sue on the contract when it occurs: and the heir of the promisor can be sued under the same circumstances. 26 A stipulation for a conveyance this year, or this month, cannot be sued upon until the whole year, or the whole month, has elapsed: 27 and similarly the promisee cannot sue immediately upon a stipulation for the conveyance of an estate or a slave, but only after allowing a sufficient interval for the conveyance to be made. TITLE XX. OF FIDEJUSSORS OR SURETIES Very often other persons, called fidejussors or sureties, are bound for the promisor, being taken by promises as additional security. 1 Such sureties may accompany any obligation, whether real, verbal, literal or consensual: and it is immaterial even whether the principal obligation be civil or natural, so that a man may go surety for the obligation of a slave either to a stranger or to his master. 2 A fidejussor is not only bound himself, but his obligation devolves also on his heir' 3 and the contract of suretyship may be entered into before no less than after the creation of the principal obligation. 4 If there are several fidejussors to the same obligation, each of them, however many they are, is liable for the whole amount, and the creditor may sue whichever he chooses for the whole; but by the letter of Hadrian he may be compelled to sue for only an aliquot part, determined by the number of sureties who are solvent at the commencement of the action: so that if one of them is insolvent at that time the liability of the rest is proportionately increased. Thus, if one fidejussor pay the whole amount, he alone suffers by the insolvency of the principal debtor; but this is his own fault, as he might have availed himself of the letter of Hadrian, and required that the claim should be reduced to his rateable portion. 5 Fidejussors cannot be bound for more than their principal, for their obligation is but accessory to the latter's, and the accessory cannot contain more than the principal; but they can be bound for less. Thus, if the principal debtor promised ten aurei, the fidejussor can well be bound for five, but not vice versa; and if the principal's promise is absolute, that of the fidejussor may be conditional, though a conditional promise cannot be absolutely guaranteed, for more and less is to be understood of time as well as of quantity, immediate payment being regarded as more, and future payment as less. 6 For the recovery of anything paid by him for the principal the fidejussor can sue the latter by the action on agency. 7 A fidejussor may be taken in Greek, by using the expressions 'tei emei pistei keleuo,' 'lego,' 'thelo,' or 'boulomai'; and 'phemi' will be taken as equivalent to 'lego.'