When Leonardo was painting The Last Supper, spectators would visit and sit quietly just so they could watch him work. The creation of art, like the discussion of science, had become at times a public event. According to the account of a priest, Leonardo would “come here in the early hours of the morning and mount the scaffolding,” and then “remain there brush in hand from sunrise to sunset, forgetting to eat or drink, painting continually.” On other days, however, nothing would be painted. “He would remain in front of it for one or two hours and contemplate it in solitude, examining and criticizing to himself the figures he had created.” Then there were dramatic days that combined his obsessiveness and his penchant for procrastination. As if caught by whim or passion, he would arrive suddenly in the middle of the day, “climb the scaffolding, seize a brush, apply a brush stroke or two to one of the figures, and suddenly depart.”
Leonardo’s quirky work habits may have fascinated the public, but they eventually began to worry Ludovico Sforza. Upon the death of his nephew, he had become the official Duke of Milan in early 1494, and he set about enhancing his stature in a time-honored way, through art patronage and public commissions. He also wanted to create a holy mausoleum for himself and his family, choosing a small but elegant church and monastery in the heart of Milan, Santa Maria delle Grazie, which he had Leonardo’s friend Donato Bramante reconstruct. For the north wall of the new dining hall, or refectory, he had commissioned Leonardo to paint a Last Supper, one of the most popular scenes in religious art.
At first Leonardo’s procrastination led to amusing tales, such as the time the church prior became frustrated and complained to Ludovico. “He wanted him never to lay down his brush, as if he were a laborer hoeing the Prior’s garden,” Vasari wrote. When Leonardo was summoned by the duke, they ended up having a discussion of how creativity occurs. Sometimes it requires going slowly, pausing, even procrastinating. That allows ideas to marinate, Leonardo explained. Intuition needs nurturing. “Men of lofty genius sometimes accomplish the most when they work least,” he told the duke, “for their minds are occupied with their ideas and the perfection of their conceptions, to which they afterwards give form.
Isaacson’s previous biographical subjects include Albert Einstein, Benjamin Franklin, Ada Lovelace, and Steve Jobs—all blue-sky thinkers, with insatiable, lifelong appetite for knowledge and the ability “to make connections across the disciplines” and “to marry observation and imagination.”