Do chimpanzees think? Can they understand cause and effect, plan ahead, or invent solutions to novel problems? These were radical questions in the early twentieth century, and Wolfgang Köhler answered them with a series of elegant, now famous experiments. In The Mentality of Apes, he presents a vivid account of chimpanzees who stack boxes to reach hanging fruit, join sticks to rake in food, and navigate complex detours—all with what appears to be a flash of insight rather than blind fumbling. This groundbreaking work introduced the concept of insight learning and helped launch the Gestalt school of psychology. Yet for today's reader, the original text can feel distant in language and style. This modern edition renders Köhler's observations and reasoning in clear, accessible English while preserving every essential detail of his argument. You will meet his remarkable subjects—Sultan, Grande, Chica—and watch their intelligence unfold. Part of The Modern Wisdom Library.