In many religious, philosophical, and mythological traditions, the soul is the incorporeal essence of a living being.[1] Soul or psyche (Ancient Greek: ψυχή psykhḗ, of ψύχειν psýkhein, "to breathe") comprises the mental abilities of a living being: reason, character, feeling, consciousness, qualia, memory, perception, thinking, etc. Depending on the philosophical system, a soul can either be mortal or immortal.[2]

Greek philosophers, such as Socrates, Plato, and Aristotle, understood that the soul (ψυχή psūchê) must have a logical faculty, the exercise of which was the most divine of human actions. At his defense trial, Socrates even summarized his teachings as nothing other than an exhortation for his fellow Athenians to excel in matters of the psyche since all bodily goods are dependent on such excellence (Apology 30a–b).

In Judaism and in some Christian denominations, only human beings have immortal souls (although immortality is disputed within Judaism and the concept of immortality may have been influenced by Plato).[3] For example, the Catholic theologian Thomas Aquinas attributed "soul" (anima) to all organisms but argued that only human souls are immortal.[4] Other religions (most notably Hinduism and Jainism) hold that all living things from the smallest bacterium to the largest of mammals are the souls themselves (Atman, jiva) and have their physical representative (the body) in the world. The actual self is the soul, while the body is only a mechanism to experience the karma of that life. Thus if we see a tiger then there is a self-conscious identity residing in it (the soul), and a physical representative (the whole body of the tiger, which is observable) in the world. Some teach that even non-biological entities (such as rivers and mountains) possess souls. This belief is called animism.[5]