“Books will soon be obsolete in schools,” opined Thomas Edison in 1913. He believed the motion picture would replace texts and teachers as means of instruction, and that it would happen within a decade. A century later, Mr Edison is unwilling to admit error, no matter how hard your correspondent probes. He insists his prediction was “not entirely incorrect”, and that he got it “both right and wrong”. The best he will offer is that it was “perhaps a bit premature”.