For more than thirty years — half his life — he was obsessively devoted to investigating everything in the natural world. Nothing escaped his interest, including how our eyes see, why the sky is blue, what forces build mountains, how light travels, where water comes from, and, most fascinating of all to Leonardo, the inner workings of the human body. Nothing stopped him. It was illegal to dissect human corpses, so he did autopsies in secret, even devising a clever way to slice through eyeballs (notoriously squishy!). Scrupulously researched and juicily anecdotal, Kathleen Krull's portrait of Leonardo will not only change children's ideas of who he was, but also what it means to be a scientist.