“Another analogy he made was comparing the way that light, sound, magnetism, and the percussion reverberations caused by a hammer blow all disseminate in a radiating pattern, often in waves. In one of his notebooks he made a column of small drawings showing how each force field spreads. He even illustrated what happened when each type of wave hits a small hole in the wall; prefiguring the studies done by Dutch physicist Christiaan Huygens almost two centuries later, he showed the diffraction that occurs as the waves go through the aperture. Wave mechanics were for him merely a passing curiosity, but even in this his brilliance is breathtaking.”