The introduction of personal computers and the Internet may have been gradual, not significantly different, in terms of the time taken, from electrification. 16 However, as Brynjolfsson and McAfee have observed, it is perfectly possible that the digital revolution is still far from having worked all its effects on productivity.
Even if it is apparently gradual, the nature of technical progress in the digital age, they say, is exponential, as in the ancient (Persian) legend in which grains of rice placed on a chessboard must be doubled from one square to the next: the volume is almost negligible at first but in the second half of the board it becomes overwhelming.