A joke is at most a temporary rebellion against virtue, and its aim is not to degrade the human being but to remind him that he is already degraded.
A good joke will sell quicker than a good poem, and, measured in sweat and blood, will bring better remuneration.
A dirty joke is not, of course, a serious attack upon morality, but it is a sort of mental rebellion.
A difference of taste in jokes is a great strain on the affections.