Isaacson writes of how he was very much an art for art’s sake person, one who preferred the conception of a piece of work to the execution of it, and continually tinkered with his creations, leaving much work unfinished, and kept the Mona Lisa with him till his death. The book details how da Vinci was basically self-taught, and how his painting used shading and blurry edges to show movement and dimension, and sculpture had twists and turns to accomplish the same dynamism. Isaacson writes of how da Vinci was just so curious about how things work and would doggedly pursue the answers, with the method to look carefully at things and separate out each detail. An example of this, which also aided in his artwork, was da Vinci's work in the field of anatomy, resulting in his incredibly precise writings about ratios in parts of the human body. Also, da Vinci worked hard at perspective in his art, keeping in mind people would view large works like The Last Supper from different vantage points.
In the conclusion to the book Isaacson notes da Vinci's ability to apply imagination to intellect and lists out what he views as lessons of Leonardo: