I am really confused about this expression supposed to mean to be confused about. Le Petit Robert only explains "(y) perdre son latin", while I came across with "en perdre son latin" as well. Do they mean exactly the same thing? After all the pronouns "y" and "en" are to signify opposite directions. My assumption is that "y perdre son latin" is to be confused about something, not to understand something, while "en perdre son latin" is to be confused because of something. If this is correct I can imagine situations where it is interchangeable, but certainly not always. Am I on the right path?