Content Warning: This section of the guide includes discussion of antigay bias.

In the Introduction, Isaacson presents Leonardo da Vinci as a vivid embodiment of the Renaissance ideal: a polymath whose insatiable curiosity spanned art, science, anatomy, optics, engineering, and natural observation. Leonardo’s notebooks—over 7,200 pages of sketches, observations, inventions, and whimsical questions—serve as the foundation for the biography and as a window into his uniquely imaginative mind. Isaacson argues that Leonardo’s genius was not divine or otherworldly, but human—based in observational skills, curiosity, and an ability to connect seemingly unrelated disciplines. The chapter explores Leonardo’s “to-do” lists, eccentric habits, and unfinished works, portraying a man driven less by deadlines than by a joyous desire to understand the world. Isaacson situates Leonardo within a historical context while acknowledging the myths, gaps, and embellishments in early biographical accounts. Ultimately, the chapter celebrates Leonardo’s human imperfections and urges readers to emulate his curiosity, wonder, and willingness to blend disciplines. Isaacson sets out to tell Leonardo’s story through the lens of his notebooks, inviting readers to appreciate how curiosity fuels creativity.