'I'll settle on one now, Ben. By the time I reached Oxford, that pendulum-clock I'd seen on the table of Huygens's house in the Hague had been perfected, and set into motion. The first clock worthy of the name. Galileo had timed his experiments by counting his pulse or listening to musicians; but after Huygens we used clocks, which – according to some – told absolute time, fixed and invariant. God's time. Huygens published a book about it later; but the clock first began to tick, and the Time of Natural Philosophy began, in the year of Our Lord – '