The book "Expression of Emotions in Man and Animals" by Charles Darwin is an outstanding scientific study devoted to the study of expressions of emotions in both humans and animals. Darwin analyzes both physiological and behavioral aspects of facial expressions and reveals their nature through the prism of evolutionary development. The author offers a deep look at the nature of emotions and their expression, revealing the mystery of these processes in everyday situations and in the natural environment. The book is an important contribution to the understanding of animal and human psychology and behavior, and also enriches our understanding of the commonality of emotional expressions in different species.