he truthful declaration of a sincere
purpose, and in their execution an equal loyalty to the truth, even though
it involve inconvenience, cost, or loss. The words of a promise may often
bear more than one interpretation; but it is obviously required by
veracity that the promiser should fulfil his promise in the sense in which
he supposed it to be understood by him to whom it was made.

There are *cases in which a promise should not be kept.* The promise to
perform an immoral act is void from the beginning. It is wrong to make it,
and a double wrong to keep it. The promise to perform an act, not
intrinsically immoral, but unlawful, should be regarded in the same light.
If both parties were aware, when the promise was made, of the unlawfulness
of the act, then neither party has the right to deem himself injured by
the other. If, however, the promiser was aware of the unlawfulness of his
promise, while the promisee supposed it lawful, the promiser, though not
bound by his promise, is under obligation to remunerate the promisee for
his disappointment or loss. If the act promised becomes unlawful between
the making and the execution of the promise, the promise is made void, and
the promisee has no ground of complaint against the promiser. Thus, if a
man promised to send to a correspondent goods of a certain description at
a certain time, and before that time the exportation of such goods were
prohibited by law, he would be free both from his promise and from
responsibility for its non-fulfilment.

A promise neither immoral nor unlawful, but made under a mistake common to
both parties, and such as--had it been known--would have prevented the
promise, is void. An extorted promise to perform an immoral or unlawful
act cannot be binding. One has, indeed, no moral right to make such a
promise, though if the case be one of extreme urgency and peril,
extenuating circumstances may reduce the wrong to an infinitesimal
deviation from the right; but, when the duress is over, no considerations
can justify the performance of what it was wrong to promise. But a
promise, not in itself immoral or unlawful, is binding, though made under
duress. Thus, if a man attacked by bandits has had his life spared on
condition of a pecuniary ransom, he is bound to pay the ransom; for at the
moment of peril he thought his life worth all he promised to give for it,
and it is neither immoral nor unlawful to give money, even to a robber. In
a case like this