The heaviness of being successful was replaced by the lightness of being a beginner again, less sure about everything. - Walter Isaacson

Sometimes, to relieve stress, he would soak his feet in the toilet, a practice that was not as soothing for his collegues.

This inability to ground his fantasies in reality has generally been regarded as one of Leonardo’s major failings. Yet in order to be a true visionary, one has to be willing to overreach and to fail some of the time. Innovation requires a reality distortion field. The things he envisioned for the future often came to pass, even if it took a few centuries. Scuba gear, flying machines, and helicopters now exist. Suction pumps now drain swamps. Along the route of the canal that Leonardo drew there is now a major highway.

Physics could teach everything about the universe except why. That led to what he calls his adolescent existential crisis. “I began trying to figure out what the meaning of life and the universe was,” he says. “And I got real depressed about it, like maybe life may have no meaning.