Nominally, this book is science fiction, but I think the label, stigmatized as it is, belies a greater depth. Good science fiction is supposed to open our minds to possibilities and scenarios we otherwise would not have encountered. It makes us think about issues that fly under our radar in everyday life. "Flowers for Algernon" does just that. Charlie Gordon is mentally handicapped (retarded or moronic in the parlance of the day) but wants very badly to learn and be smart. He's chosen to be the first human subject of an experiment designed to increase intelligence. As the experiment succeeds, Charlie quickly surpasses the great minds around him while at the same time experiencing disorienting resurfaced memories and the prospect that his intelligence might not be permanent.
What Keyes forces us to confront is our idea of what makes a human human. Charlie's main complaint is that the people he considered to be his friends as well as the scientists he must thank for his new-found intelligence did not think of him as a human being before the experiment. It's such a powerful message that I'm surprised the book hasn't been mass produced and distributed by organizations who advocate for the mentally handicapped. Keyes wants us to understand that personhood is not a product of intelligence, but of emotion. This is a powerful book, and a wonderful example of what makes science fiction great.