Flowers for Algernon - Daniel Keyes

The classic novel about a daring experiment in human intelligence Charlie Gordon, IQ 68, is a floor sweeper and the gentle butt of everyone's jokes - until an experiment in the enhancement of human intelligence turns him into a genius. But then Algernon, the mouse whose triumphal experimental tranformation preceded his, fades and dies, and Charlie has to face the possibility that his salvation was only temporary.