It is at first very evident that obligation supposes a being capable of fulfilling it, that duty is applied only to a free being. Then the nature of obligation is such, that if we are delinquent in fulfilling it, we feel ourselves culpable, whilst if, instead of understanding our interest well, we have understood it ill, there follows only a single thing, that we are unfortunate. Are, then, being culpable and being unfortunate the same thing? These are two ideas radically different. You may advise me to understand my interest well, under penalty of falling into misfortune; you cannot command me to see clearly in regard to my interest under penalty of crime. Imprudence has never been considered a crime. When it is morally accused, it is much less as being wrong than as attesting vices of the soul, lightness, presumption, feebleness. As we have said, our true interest is often most difficult of discernment. Obligation is always immediate and manifest. In vain passion and desire combat it; in vain the reasoning that passion trains for its attendance, like a docile slave, tries to smother it under a mass of sophisms: the instinct of conscience, a cry of the soul, an intuition of reason, different from reasoning, is sufficient to repel all sophisms, and make obligation appear. However pressing may be the solicitations of interest, we may always enter into contest and arrangement with it. There are a thousand ways of being happy. You assure me that, by conducting myself in such a manner, I shall arrive at fortune. Yes, but I love repose more than fortune, and with happiness alone in view, activity is not better than sloth. Nothing is more difficult than to advise any one in regard to his interest, nothing is easier than to advise him in regard to honor. After all, in practice, the useful is resolved into the agreeable, that is to say, into pleasure. Now, in regard to pleasure, every thing depends on humor and temperament. When there is neither good nor evil in itself, there are no pleasures more or less noble, more or less elevated; there are only pleasures that are more or less agreeable to us. Every thing depends on the nature of each one. This is the reason why interest is so capricious. Each one understands it as it pleases him, because each one is the judge of what pleases him. One is more moved by pleasures of the senses; another by pleasures of mind and heart. To the latter, the passion of glory takes the place of pleasures of the senses; to the former, the pleasure of dominion appears much superior to that of glory. Each man has his own passions, each man, then, has his own way of understanding his interest; and even my interest of to-day is not my interest of to-morrow. The revolutions of health, age, and events greatly modify our tastes, our humors. We are ourselves perpetually changing, and with us change our desires and our interests.