Saint Saens was apparantly the greatest sight reader ever.
A passage from "The Great Pianists" by Schonberg:
Von Bulow, St. Saens and Wagener were all in conversation. Saint waens, who could not follow in German became bored and piecked up a full-score manuscript of Siegried, not yet completed, put it on the piano and began to play. Wagner and Von Bulow stopped talking. Never, said von bulow, had he heard such score reading, it was all at first sight. Scarecely an effect was lost, the player seemed intuitively to grasp the whole structure of the work and he reporduced it in its transformed shape without a second's hesitiation. Wagner was speechless. "I too can play from score," said von bulow, "but neither I nor any living man could have performed that feat after Saint saens. he is the greatest musical mind of our time."