According to Plato, the soul is the immortal essence of a person that exists before birth and after death.

According to Aristotle, the soul is the form of the body, which gives it its life and function.

According to Descartes, the soul is a thinking substance, which is distinct from the body.

According to Locke, the soul is a blank slate, which is filled with knowledge through experience.

According to Hume, the soul is a bundle of perceptions, which are constantly changing.

According to Kant, the soul is a transcendental unity of apperception, which is the condition for the possibility of experience.

According to Hegel, the soul is the Absolute Spirit, which is the highest form of reality.

According to Schopenhauer, the soul is the Will, which is the fundamental force of the universe.

According to Nietzsche, the soul is the Will to Power, which is the fundamental drive of all living things.

According to James, the soul is a stream of consciousness, which is constantly changing.

According to Bergson, the soul is a durée, which is a continuous flow of time.

According to Whitehead, the soul is a process, which is a continuous flow of events.

According to Hartshorne, the soul is a dipolar entity, which has both a physical and a mental pole.

According to Tillich, the soul is the ground of being, which is the ultimate reality from which all things come.

According to Levinas, the soul is the Other, which is the source of all meaning and value.