Flowers for Algernon

I always include major spoilers (hidden), to help with my memory issues. Read them at your peril! 

Heartbreaking, profound, short story about a man of very low intelligence, who agrees to an operation to triple his IQ, and the difficult consequences of that decision. With cleverness, there also comes a painful awareness of others, their true opinions and failings. His  previous contentment is gone as he realises that his “friends” were not laughing with him, but at him. Eventually he is comprehensively rejected. He becomes so intelligent that the scientists who are studying him are uncomfortable around him. As was feared all along , he loses his intelligence as fast as he gained it, even as he struggles to cling on long enough to leave something of value behind him.   The ending is really sad. I have never been moved to tears by a short story before.