Man is indeed a kind of bridge. He is the point at which the material world and the spiritual world meet and mingle and thus occupies a special place in the matrix of the created order.
Through man, the material world is lifted up into the spiritual realm, and through their combination in man we see that the two are compatible, each with the other. Material being is not a thing along side of which the spirit leads an unconnected and indivisible existence. The unity of creation is demonstrated at the point where the two are united in man. That gives him a special function: that is to say, sharing the responsibility for the unity of creation, incarnating spirit in himself and, conversely, lifting material being up to God -- and thereby, all in all, making a contribution to the great symphony of creation.
-- Joseph Cardinal Ratzinger
God and the World