Peter Sís’s picture book biography of Charles Darwin is as complex as Darwin’s contributions to modern science. Beginning with the endpapers, not an inch of any page is left uncovered. Intricate drawings, text boxes, diagrams, and maps are accompanied by several strands of text differentiated by font and size. In one narrative strand, there is an account of Darwin’s life from childhood on. In the second, additional detail about Darwin’s private life is revealed. In the third, readers have access to Darwin’s secret thoughts and hypotheses—ideas he knew were radical and risky to make public. Finally, there are excerpts from Darwin’s journals. The first three threads are significant, because Darwin led a very secret intellectual life in a society that was not always eager to embrace scientific change, particularly not when those discoveries threatened the beliefs of the Christian Church. While the additional source documentation would have been helpful, this is nonetheless a significant work that illuminates Darwin’s life and times for children and teens. (Ages 10–16)