Where do we learn what "creation" means?

“It is from this experience of God’s free personal activity within history that the confession of God as Creator of the world ... also acquires its specific vitality and clarity.... The New Testament (like the Old) accepts its knowledge of the world’s createdness in the strict sense from the God who speaks and reveals himself. Further, man only really learns what creating is from God’s free and powerful activity in history, unconstrained by any prior obligation.”

—Karl Rahner, Theological Investigations I (London: Darton, 1961), p. 107.