3510 When the reason for a rule ceases, so should the rule itself.

3511 Where the reason is the same, the rule should be the same.

3512 One must not change his purpose to the injury of another

3513 Anyone may waive the advantage of a law intended solely for his benefit. But a law established for a public reason cannot be contravened by a private agreement.

3514 One must so use his own rights as not to infringe upon the rights of another.

3515 He who consents to an act is not wronged by it.

3516 Acquiescence in error takes away the right of objecting.

3517 No one can take advantage of his own wrong.

3518 He who has fraudulently dispossessed himself of a thing may be treated as if he still had possession.

3519 He who can and does not forbid that which is done on his behalf, is deemed to have bidden it.

3520 No one should suffer by the act of another.

3521 He who takes the benefit must bear the burden.

3522 One who grants a thing is presumed to grant also whatever is essential to its use.

3523 For every wrong there is a remedy.

3524 Between those who are equally in the right, or equally in the wrong, the law does not interpose.

3525 Between rights otherwise equal, the earliest is preferred.

3526 No man is responsible for that which no man can control.

3527 The law helps the vigilant, before those who sleep on their rights.

3528 The law respects form less than substance.

3529 That which ought to have been done is to be regarded as done, in favor of him to whom, and against him from whom, performance is due.

3530 That which does not appear to exist is to be regarded as if it did not exist.

3531 The law never requires impossibilities.

3532 The law neither does nor requires idle acts.

3533 The law disregards trifles.

3534 Particular expressions qualify those which are general.

3535 Contemporaneous exposition is in general the best.

3536 The greater contains the less.

3537 Superfluity does not vitiate.

3538 That is certain which can be made certain.

3539 Time does not confirm a void act.

3540 The incident follows the principal, and not the principal the incident.

3541 An interpretation which gives effect is preferred to one which makes void.

3542 Interpretation must be reasonable.

3543 Where one of two innocent persons must suffer by the act of a third, he, by whose negligence it happened, must be the sufferer.

3545 Private transactions are fair and regular.

3546 Things happen according to the ordinary course of nature and the ordinary habits of life.

3547 A thing continues to exist as long as is usual with things of that nature.

3548 The law has been obeyed.