In current scientific debates, the reference to Charles Darwin and the theory of natural selection is constant. But who is the man who has so marked the history of the natural sciences? In this film, Darwin reveals himself through extracts from his autobiography or from his letters. He shares with us his enthusiasm, his doubts, his affections. He tells us about his lack of interest in school, his passion for beetles, and then, through his logbook, his trip to South America aboard the Beagle. The commentary recounts Darwin in his time, in his scientific and family environment, and recounts the determining moments in his life. He explains the dominant ideas of his time, the fixity of species that Darwin would increasingly doubt. From his scientific background, he recounts the support of his friends who push Darwin to publish his theory and who vigorously defend him in debates such as the Oxford battle between science and religion. The commentary also gives the essential elements of Darwinian theory. He situates it in contemporary science. To this dialogue between an inner voice and an outer voice corresponds an image that interweaves real images and period documents. The film discovers the places where Darwin lived, but the images are also seen by Darwin. Like him, they marvel at nature. Through a confusion of scales, they reveal astonishing correspondences of the unity of living things. Engravings, drawings, paintings, letters, help us to give human presence. The dialogues between Darwin and the commentary, the images and the soundtrack, combine poetry and science. They help us to know and feel from within, and, like Darwin, to question ourselves.