Leonardo was one of history’s most disciplined observers of nature, but his observation skills colluded rather than conflicted with his imaginative skills. Like his love of art and science, his ability to both observe and imagine were interwoven to become the warp and woof of his genius.

But Leonardo did not remain merely a disciple of experiments. His notebooks show that he evolved. When he began absorbing knowledge from books in the 1490s, it helped him realize the importance of being guided not only by experiential evidence but also by theoretical frameworks. More important, he came to understand that the two approaches were com

The goal of Leonardo’s argument was to elevate the work of painters—and their social status—by linking their art to the science of optics and the mathematics of perspective. By exalting the interplay between art and science, Leonardo wove an argument that was integral to understanding his genius: that true creativity involves the ability to combine