This deduction is very ingenious; but it lacks strictness, inasmuch as it is based on the use a man may be made of, which principle is contrary to the general principle of Kant's morals, and also because it rests on the standpoint of social interest, which lies outside the point in question. =155. Discretion.=--It is evident that the duty not to lie, does not carry with it, as its consequence, the duty of telling all. Silence must not be confounded with dissimulation, and no one is obliged to tell all he has in his mind; far from it; we are here before another duty toward ourselves, which stands in some respect in opposition to the preceding one, namely, _discretion_. The babbler who speaks at all times and under all circumstances, and he who tells what he should not, must not be confounded with the loyal and sincere man, who only tells what he thinks, but does not necessarily tell all he thinks. Silence is obviously a strict duty toward others, when the matter in question has been confided to us under the seal of secrecy. But it may also be said that it is a duty toward ourselves, and for the following reasons: 1. To use one's mind, as does the babbler, in giving utterance to barren and frivolous thoughts, is degrading: not all that accidentally crosses one's mind is worthy of being expressed; and it is simply heedlessness to fix one's mind on fleeting things, and give them a certain fixity and value through words; 2, there are, on the other hand, other thoughts, too precious, too personal, too elevated, to be indiscreetly exposed to the curiosity of fools or indifferent persons. Thus will it be heroic, unquestionably, to confess one's faith before the executioner, if there is need; but it is not necessary to proclaim it all round when there is no occasion for it: I believe such and such a thing; I belong to such or such a church; I hold such and such a doctrine; I belong to such or such a party, unless, of course, there is an interest in spreading one's belief; and even then it will be necessary to choose the right place and the right moment. As to using discretion in regard to our sentiments, our moral qualities, or our defects, it is in one instance a duty of modesty and in another one of personal dignity. =156. Perjury.=--If falsehood is in general an abasement of human dignity, it is a still greater abasement when it is of the kind called _perjury_, and a transgression which might be defined as a double falsehood. Perjury is of two sorts: it either means swearing falsely or violating a former oath. In order to understand the meaning of perjury, one must know what constitutes an oath.