The former is easy, the latter hard. —Leonardo da Vinci (c. 1490) THE FROG JUST wouldn’t die. Gradually, methodically, Leonardo had removed its head, its heart, its intestines, and even its skin, but the animal still showed signs of life. The year was 1487, and Leonardo’s investigations were proliferating with an almost Malthusian relentlessness. Architecture was on his mind: in his notebooks that year he played with a variety of ideas for the tiburio of the cathedral of Milan, and on page after page doodled a dreamy procession of arches and columns, domes and churches, temples and palaces. But he did much more. He roughed out preliminary studies for paintings and statues. He sketched people and animals, landscapes and plants. He designed an ideal city and drew maps. Incessantly, almost involuntarily, he invented things: cannons, ditch diggers, a device for raising and lowering curtains, water pumps, flying machines, musical instruments, a parachute, stage props, underwater breathing devices, submarines.
