text, Grasset introduces the unconventional choice of analyzing medical themes in Bourget's literature, contrasting it with more direct portrayals of medical life found in other authors. He emphasizes that the essence of medicine should be understood as biological knowledge concerning human life, rather than merely clinical practice. The opening discusses Bourget's nuanced portrayals of various medical characters and types, foreshadowing a detailed exploration of how these representations relate to broader biological concepts such as heredity and environmental influences on individual identity. Grasset's introductory remarks set the stage for an analytical examination of Bourget's work through a medical lens, inviting readers to consider the deeper implications of his narratives. (This is an automatically generated summary.)