Only the Spirit of the Holy One can impart to the human spirit the knowledge of the holy. Yet as electric power flows only through a conductor, so the Spirit flows through Truth and must find some measure of Truth in the mind before It can illuminate the heart. Faith wakes at the voice of truth but responds to no other sound... Still, there must be humble penitence in the heart before Truth can produce faith.
Maybe the burning bush was burning all the time and Moses didn't notice. Maybe the miracle is when you stop and pay attention.