Fana is annihilation — the passing away of the sense of a separate self in the overwhelming presence of God — and it is the point at which Sufism's language becomes dangerous. Al-Hallaj said "I am the Truth" in the tenth century and was executed for it; the tradition's more careful teachers describe fana as followed by baqa, subsistence, in which the self returns able to function, and treat any permanent claim to divinity as a failure to complete the transit.