Unconscious Memory, written in the late 19th century, examines memory as an unconscious process shaping the behavior and development of organisms. Butler argues that ancestral actions and experiences are transmitted as unconscious memories, forming the basis of instinct and habit. He critiques Darwin’s theory of natural selection while highlighting the limitations of earlier evolutionists, contrasting their ideas with his own. Central to his thought is the attempt to interpret life’s progress through the interplay of memory and habit. The work stands as both a biological and philosophical inquiry, expanding evolutionary theory and probing the boundary between consciousness and the unconscious.