Sigmund Freud's early influences, particularly his work on hysteria and neurosis, laid the foundation for psychoanalysis. Freud's exploration of the unconscious mind revealed that behaviors are driven by hidden desires and conflicts. His introduction of concepts such as the id, ego, and superego provided a framework for understanding human psychology. Freud's emphasis on childhood experiences, particularly sexual development, shaped therapeutic techniques, fostering a deeper understanding of mental health. His pioneering work shifted the focus of psychology from observable behaviors to the internal psychological processes, influencing psychiatry and therapy practices profoundly.