If what we call virtue be only virtuous _because_ it is useful, it can only be virtuous _when_ it is useful. The question of the morality of a large number of acts must therefore depend upon the probability of their detection,(71) and a little adroit hypocrisy must often, not merely in appearance but in reality, convert a vice into a virtue. The only way by which it has been attempted with any plausibility to evade this conclusion has been by asserting that the act would impair the disposition of the agent, or in other words predispose him on other occasions to perform acts which are generally hurtful to society. But in the first place a single act has no such effect upon disposition as to counteract a great immediate good, especially when, as we have supposed, that act is not a revolt against what is believed to be right, but is performed under the full belief that it is in accordance with the one rational rule of morals, and in the next place, as far as the act would form a habit it would appear to be the habit of in all cases regulating actions by a precise and minute calculation of their utility, which is the very ideal of utilitarian virtue. If our enquirer happens to be a man of strong imagination and of solitary habits, it is very probable that he will be accustomed to live much in a world of imagination, a world peopled with beings that are to him as real as those of flesh, with its joys and sorrows, its temptations and its sins. In obedience to the common feelings of our nature he may have struggled long and painfully against sins of the imagination, which he was never seriously tempted to convert into sins of action. But his new philosophy will be admirably fitted to console his mind. If remorse be absent the indulgence of the most vicious imagination is a pleasure, and if this indulgence does not lead to action it is a clear gain, and therefore to be applauded. That a course may be continually pursued in imagination without leading to corresponding actions he will speedily discover, and indeed it has always been one of the chief objections brought against fiction that the constant exercise of the sympathies in favour of imaginary beings is found positively to indispose men to practical benevolence.(72)