The astronomer pressed an eye socket to his telescope, picked up his quill, and wrote down a very long string of numbers. For a split second, writes Leibniz, a sunbeam happened to align precisely with the warped slat of the window blind and blasted the interior of the observatory with a brilliant light, “excruciating after such a prolonged spell of continuous quasi-darkness.” Leibniz shielded his eyes. On the astronomer’s lap the cat opened his eyes, which gleamed crazily in the sunlight, “and therefore existed.” Then the Earth rotated a little bit and the light was gone. It was now ten o’clock “on the dot,” reported Leibniz to the Philosophical Transactions, in my translation. One hour had gone by, and if the astronomer was right about the eclipse, there were two more still to go.

THREE