Southwood Smith opens this 1847 volume by drawing a sharp line between the organic and animal lives within the human body. The organic organs—stomach, liver, intestines—are single and asymmetrical, while those of animal life—brain, senses, muscles—are double and symmetrical. This structural contrast, he argues, reflects two distinct but coordinated systems: one for maintenance and growth, the other for sensation and motion. Smith, a physician to the London Fever Hospital, does not merely catalog anatomy; he uses these differences to frame a broader inquiry into how physical constitution shapes human longevity and happiness.

Symmetry and Asymmetry in the Body

Smith devotes careful attention to the body's symmetrical form, noting that a median line divides the well-formed body into two equal halves. This symmetry, he observes, is not universal: the brain and spinal cord split evenly, and the senses are paired, but the stomach, intestines, liver, and spleen are single and irregular. He uses this distinction to reinforce the separation between the organic life (nutrition, growth) and the animal life (perception, movement). The head, described as egg-shaped with the broad end behind, is both stronger and more capacious for its purpose—a design argument that recurs throughout the text.

The Architecture of the Skull

Smith enumerates the eight bones of the cranium, distinguishing six proper to the skull and two shared with the face. He names the frontal, parietal, temporal, occipital, sphenoid, ethmoid, and maxillary bones, and includes detailed figures of the skull from front, side, and base. This anatomical precision serves a philosophical end: the skull's structure, he implies, is perfectly adapted to protect the central organ of the nervous system. The joints and ligaments that attach the head to the spinal column are described as exceeding strong, reinforcing his theme of purposeful design in the human frame.

Pleasure as a Physiological Principle

Smith proposes that pleasure is the direct, ordinary, and gratuitous result of organ action. He identifies sources of pleasure in the organic organs' influence on consciousness, in the animal appetites, senses, intellectual faculties, and in both selfish and sympathetic affections. Pleasure, he argues, is conducive to the development of organs and the continuance of their action. This is not a hedonistic claim but a physiological one: the body is wired to seek what sustains it. The progress of human knowledge and happiness, he suggests, are linked to understanding this relationship between physical condition and well-being.

Smith's approach combines minute anatomical description with a moral-philosophical framework. Readers should attend to how he moves from bone counts and symmetry to arguments about longevity and pleasure. The excerpts show a writer who treats the body as a text to be read for evidence of design and purpose. This volume rewards those who read slowly, following the thread from the skull's eight bones to the claim that happiness is built into our physiology.