This book investigates the biological and chemical foundations of human consciousness and mental function. Gordon Rattray Taylor, a science writer and journalist, synthesizes mid-20th-century neurological research to explain how physical brain processes manifest as complex psychological phenomena. He argues that the mind is an emergent property of the brain's electrical and chemical activity, providing a framework that bridges the gap between hard biology and subjective experience.

Readers frequently note the accessible, journalistic prose style that makes complex neurological concepts understandable for a general audience. Experts highlight this as a significant historical synthesis of brain research that reflects the scientific understanding of the mind during the era in which it was written.