Soul (نَفْس, *nafs*) is a spiritual, immaterial substance.

Influenced by Aristotle, Neoplatonism, and Qur’anic revelation.

Avicenna: soul is simple, incorporeal, and individuated at creation.

Soul progresses through stages: vegetative, animal, rational.

Mystical traditions (e.g., Sufism) focus on purification of the soul.

Philosophical arguments for immortality and resurrection abound.