“I awoke” he wrote, “turned on the light and jotted down a few notes on a tiny slip of thin paper. Then I fell asleep again. It occurred to me at 6.00 o’clock in the morning that during the night I had written down something important, but I was unable to decipher the scrawl. The next night, at 3.00 o’clock, the idea returned. It was the design of an experiment