An Introduction to the Devout Life continues, with comments on chastity: why everybody needs to practice this virtue in a way appropriate to their state in life, and what kind of things you can do to gain or strengthen this virtue in yourself.
Yes, it’s kinda annoying when authors talk about sins without actually coming right out and saying what they are, even in the infamous “let’s break into Latin and Greek” clarifications. On the other hand, think how much utility ambiguity has, to cover a multitude of possible sins! (Sorry, no annotations in the translation I’m reading from. I’m sure some of the others will tell you their best guesses. Or you can go read St. John Cassian, who was an awesome writer and interviewer of desert monks, or Tertullian’s little book. I want breakfast more than scholarship at the moment.) Anyway, I’m sure you know what your own problems are with chastity, if any, and you’re better off concentrating on that.