Walter Isaacson is on a quest. To understand his Leonardo Da Vinci you have to understand something of why he choose to write a biography about him at all, after writing biographies of Steve Jobs and Albert Einstein. Thankfully, Isaacson is explicit about what interests him in these personages and so there is no need for reading between the lines.What Isaacson wants to understand is what makes some men and women people of genius. Not the silly way genius is portrayed in the movie Amadeus, in which it is simply some innate talent, but the character traits which enable rare individuals with the capacity to permanently change the world with the mere power of their mind.With that goal in mind, one is ready to appreciate Isaacson’s Leonardo Da Vinci. The book begins discussing his early achievements in art and the investigation of nature within the first forty pages, fairly quickly for a 525 page tome. And the book is dominated by appreciations of his work, both artistic and scientific (to use a modern distinction unrecognized by Leonardo). Along the way there is a wonderful resonance between Isaacson describing the characteristics of Leonardo that led to his peculiar type of genius and then seeing that genus instantiated in a particular unpublished treatise on anatomy or in a work of art such as the Mona Lisa.If you are interested in this quest, in both seeing what led to Leonardo being a genius, and then seeing that genius expressed in his creative work, you will love Isaacson’s Da Vinci. Many biographers prefer to dwell on a lengthy account of the culture and history of the time and focus on the personal life of their subject. Others choose to try to psychoanalyze their subject and allow the reader to understand the subconscious drives which led to their accomplishments.None of that is to be found in Isaacson’s work. Though a summary doesn’t do the book justice, Isaacson sees Leonardo as unusually perceptive of the world around him, with an insatiable curiosity, a proper understanding of how to balance theory and experiment and a disdain for doctrines handed on by the past. These traits, and others, led him to understand the effect of light in creating the illusion of three dimensions in painting, which muscles are used to smile, how men and women might one day be able to fly and all the many other prescient things expressed in his art and notebooks.If there is anything to criticize, it is that Isaacson is almost universally positive, almost effusively, about Leonardo. But this is because the book focuses mostly on the factors that led to this genius and the actual fruits of his intellect. Admittedly, it is hard to be critical of those aspects of Leonardo’s life.One final point to make to potential readers: Isaacson writes in clear and simple English. Though the book is 525 pages long I read it in less than a day. If he had chosen to adopt the tone of many academics this would have been a far less pleasurable, and longer, read.Isaacson set out to determine both what made Leonardo a genius and why he is considered one. While every reader can form their own opinion as to whether he was successful, I think both the importance of the quest and its achievement in the case of Leonardo will be doubted by few readers of this book.