Ten photography lessons learned from Henri Cartier-Bresson SEP 07 2011
4. Stick to one lens
Although Henri Cartier-Bresson shot with several different lenses while on-assignment working for Magnum, he would only shoot with a 50mm if he was shooting for himself. By being faithful to that lens for decades, the camera truly became "an extension of his eye".
Update: That link is having some trouble so here's the cached copy from Google.