Against Celsus 7.33

Thinking that we uphold the doctrine of the resurrection for the sake of knowing and seeing God, he strings together for himself what he wishes and says this: When they are shut out on every side and refuted, they come back again, as though they had heard nothing, to the same question: How, then, shall we know and see God? And how shall we go to him? Let anyone who wishes know, then, that even if for other purposes we need a body, in order to be in a bodily place, and one of the kind that corresponds to the nature of the bodily place, and, needing the body, we put on over the tent what has been mentioned, yet for knowledge of God we have no need of a body at all. For what knows God is not the eye of the body but the mind, which sees what is “in the image” of the Creator and has received, by the providence of God, the power to know God. And what sees God is a pure heart, from which there no longer “come evil thoughts,” nor “murders,” nor “adulteries,” nor “sexual immoralities,” nor “thefts,” nor “false witness,” nor “blasphemies,” nor “an evil eye,” nor any other wrong thing; because of which it is said, “Blessed are the pure in heart, for they shall see God.” And since our own will is not sufficient to have a wholly “pure” “heart,” but we need God, who creates it such, for this reason the one who prays with understanding says: “Create in me a clean heart, O God.”