122. The messengers of this Word are doves; that is, sincere men, without guile, and filled with the Holy Spirit. Isaiah 60, 8, likens ministers of the Gospel or of grace to doves which fly to their windows. And, though Christ commands them to imitate the harmlessness of doves, Mt 10, 16, meaning that they should be sincere and free from venom, yet, he admonishes them to be wise like serpents; that is, they should be wary of false and cunning people, and cautious like the serpent, which is said to shield its head with special skill in a fight.
123. The green freshness of the olive branch, also, is a type of the Word of the Gospel, which endureth forever and is never without fruit. Psalms 1, 3 likens those who study the Word to a tree, the leaves of which do not wither. We heard nothing like this above concerning the raven, which flew to and fro near the ark. This second dove which was sent forth is a type of the New Testament, where grace and the forgiveness of sins are promised openly through the sacrifice of Christ. This is why the Holy Spirit chose to appear in the form of a dove in the New Testament.
124. The third dove did not return. After the fulfilment of the promise given the whole world through the mouth of the dove, no new teaching is to be looked for, but we simply await the revelation of those things which we believe. Herein is certain testimony for us that the Gospel will endure unto the end of the world.
125. The text, furthermore, specifies the time Noah waited after he had first sent forth a dove, namely, seven days. These seven days typify the time of the Law which, of necessity, preceded the period of the New Testament.
126. We read, likewise, that the second dove returned at dusk, carrying the olive branch. To the Gospel the last age of the world has been assigned. Nor should we look for another kind of doctrine, for it is to an evening meal that Christ compared the Gospel (Mt 22, 2; Lk 14, 16).