"Flowers for Algernon" is the perfect example of what science fiction can do better than any other genre. By using science as a instigator of massive changes in Charley mental state it allows the author, Daniel Keyes, to examine human intellect, the desire for knowledge, love, sexuality and more in ways that could never be achieved in more traditional stories, allowing us in the end to know more about Charley than we ever could have in those stories.
"Flowers for Algernon" is the story of Charley a janitor with an IQ of 68 who wants to be smarter. He is studying at night to learn to read and write but even that simple task is nearly impossible for him. He is given the opportunity to be given a experimental surgery that will triple his IQ.
The title character of the story, Algernon, is a laboratory mouse who has been given the procedure before Charley and regularly defeats Charley at tests of intelligence early in the story as well as being an indicator throughout the story of where Charley is likely to end up.
This story is told through a journal kept by Charley. This is the key to this stories success. Charley as the narrator tells as much about his increases and eventually decreasing intelligence through the words he uses, spelling and punctuation as he does through the actual stories he tells. This keeps the focus of the story on what is important, Charley rather than attempting to deviate into other interesting but superfluous piece of the story.
There are numerous lessons and themes in this story but perhaps the most important is the reminder that people with low IQs are still people with feelings and emotions just like ours. This is most clearly seen in one of the stories Charley tells at the near peak of his intelligence of being in a restaurant when a busboy drops a stack of dishes. Charley finds himself laughing with everyone else until he sees the look in the boy's eyes and recognizes who he was previously. He then becomes angry, more at himself than anyone else.
It is this moment, along with the changing of how other people see Charley, that makes the end of this book less melancholy. In the end the effects of the operation wear off and Charley slowly reverts to his previous mental state, but even as he returns to who he was the emotional lessons seem to remain. Those who had made fun of him because they were smarter now understand better after he has, inadvertently, done the same to them.
This is one of the most powerful stories in science fiction in large part because it is so perfectly suited to the genre. Doing things that could not be realistically done in any other genre it examines the range of both human intellect and human emotion and the connections between them nearly perfectly.