The fundamental mode of knowing in Sufism is called "knowledge by presence." All other knowledge is knowledge by correspondence, which refers to conceptual knowledge. But conceptual knowledge itself must be grounded in a fundamental, epistemological act, and that is knowledge through presence -- the knowledge of immediacy, of direct experience, the unification of witness and witnessed. This is what is experienced essentially in the depths of meditation. This gives one a faith that is unshatterable.

- Pir Zia Inayat Khan