
"The Holy Dimension", p. 337.
Heschel made similar statements in earlier writings: The great insight is not attained when we ponder or infer the beyond from the here. In the realm of the ineffable, God is not a hypothesis derived from logical assumptions, but an immediate insight, self-evident as light. He is not something to be sought in the darkness with the light of reason. He is the light.
Man Is Not Alone : A Philosophy of Religion (1951)
Moral Grandeur and Spiritual Audacity: Essays (1997)
Context: In the realm of faith, God is not a hypothesis derived from logical assumptions, but an immediate insight, self-evident as light. To rationalists He is something after which they seek in the darkness with the light of their reason. To men of faith He is the light.