The origins of psychological knowledge may be said to be as old as humankind. From as early as recorded time, men and women have speculated about the nature of psychological states and processes and their relationship to human behavior. Theoretical reflections on sensation, memory, and dreaming, for example, are to be found in many ancient works, such as the Hindu sacred texts known as the Vedas (which precede the first millennium BCE) and the Assyrian “dream books” (from around the fifth millennium BCE).

Many early cultures, such as the Egyptian and Babylonian, tried to understand human psychology and behavior in terms of the activity of some immaterial “spirit” or “soul,” usually intimately associated with breath and the action of the heart and lungs. The Greek term psyche, from which the term psychology is derived, is etymologically tied to words signifying breath (pneuma) or wind. There is nothing especially remarkable about this, for at a basic level of observation, it is obvious that whatever enables the human organism to act in a purposive fashion is intimately associated with the action of the heart and lungs. When activity in these organs ceases, so also does the activity of the human organism.

Many early theories that postulated immaterial spirits or souls also maintained that such entities could enjoy a life after death in some spiritual realm. However, not all early theories were committed to the notion of an afterlife, and for those that were, it was often an impoverished and literally shady sort of thing. In Greek mythology, for example, the dead survived as shadows of their former selves, which could only be temporarily revived via blood sacrifice.

Beliefs in immaterial spirits or souls are often characterized as animistic and are associated with so-called primitive cultures today. However, we should guard against the condescending assumption that all earlier cultures explained mind and behavior in terms of immaterial spirits or souls and that humans came to a proper understanding of these matters only with the development of psychological science, as such assumptions can seriously prejudice our approach to the history of psychology. Although many ancient thinkers did embrace theories about immaterial spirits or souls, their psychological understanding was far more sophisticated – and materialistic – than is usually acknowledged.