Instruct: Classify Amazon reviews into positive or negative sentiment
Query: He really knows his subject

You have to admit - he really knows his subject.Here's the latest on him from the newswires.Sixty-one-year-old James Welles has been arrested "for allegedly trying to arrange sex with a 15-year-old girl over the Internet. The girl turned out to be an undercover male detective." Welles is the author of a pair of books, "The Story of Stupidity" and "Understanding Stupidity."