Why did Paul use 'thou shalt not covet' as the primary example of the law?

Les explains that coveting triggers all sorts of sins, even something like foul language, because people covet attention. No matter how you look at it, a person cannot break one of the Ten Commandments unless he covets first. That is why Paul uses this commandment as the primary example of the law. Paul writes that he had not known lust or desire except the law had said, "Thou shalt not covet." Then sin, or old Adam, taking occasion by the commandment, wrought in him all manner of contraptions—immoral or evil thinking. Without the law, old Adam was dead, meaning he was not functioning in the spirit realm because he was not paying attention to the law. Les also reminds us what kind of man Paul was: religious, a religious fanatic, an Israelite, a Pharisee of the Pharisees, of the tribe of Benjamin, circumcised the eighth day, the epitome of a Judaistic Jew who practiced the Jewish religion to the hilt.