There are many different kinds of sin. It is possible by a single act to commit more than one sin. And a given sin may be repeated any number of times. To get the exact number of our misdeeds we must begin by counting as many sins at least as there are kinds of sin. We might say there is an offense for every time a commandment or precept is violated, for sin is a transgression of the law. But this would be insufficient inasmuch as the law may command or forbid more than one thing. Let the first commandment serve as an example. It is broken by sins against faith, or unbelief, against hope, or despair, against charity, against religion, etc. All these offenses are specifically different, that is, are different kinds of sin; yet but one precept is transgressed. Since therefore each commandment prescribes the practice of certain virtues, the first rule is that there is a sin for every virtue violated. But this is far from exhausting our capacity for evil. Our virtue may impose different obligations, so that against it alone we may offend in many different ways. Among the virtues prescribed by the first commandment is that of religion, which concerns the exterior homage due to God. I may worship false gods, thus offending against the virtue of religion, and commit a sin of idolatry. If I offer false homage to the true God, I also violate the virtue of religion, but commit a sin specifically different, a sin of superstition. Thus these different offenses are against but one of several virtues enjoined by one commandment. The virtue of charity is also prolific of obligations; the virtue of chastity even more so. One act against the latter may contain a four-fold malice. It would be out of place here to adduce more examples: a detailed treatment of the virtues and commandments will make things clearer. For the moment it is necessary and sufficient to know that a commandment may prescribe many virtues, a virtue may impose many obligations, and there is a specifically different sin for each obligation violated. But we can go much farther than this in wrongdoing, and must count one sin every time the act is committed. "Yes, but how are we to know when there is one act or more than one act! An act may be of long or short duration. How many sins do I commit if the act lasts, say, two hours? And how can I tell where one act ends and the other begins?"