Avicenna imagined a man falling through empty air who still knows he exists

Centuries before Descartes, the Persian philosopher Avicenna asked you to picture a person created fully formed, floating in a void, with no senses touching anything — not even their own limbs. He argued that person would still be certain of one thing: their own self, showing the soul is known directly, not inferred from the body.

— Avicenna (Ibn Sina), The Book of Healing (Kitab al-Shifa) — De Anima section, c. 1027