Already in 1968, then-Professor Ratzinger wrote on the subject "Schöpfungslaube und Evolutionstheorie" ("Belief in Creation and the Theory of Evolution"), which was republished in 1973 in the book Dogma und Verkündigung. He discussed the consequences for the faith of an evolutionary view of the world. He offered the response that the theory of evolution neither destroys the faith nor confirms it, but rather presents it with a challenge. Later on, he underlined that the theory of evolution sometimes has a tendency to insist on being a full explanation of the totality of existence, which makes both metaphysics and God superfluous. Hence for him what's needed is a calm approach on both sides.