"For _the Holy Ghost was not yet_," is the more than surprising saying of Jesus when speaking of "the Spirit which they that believe on him should receive." Had not the Spirit been seen descending upon Jesus like a dove at his baptism, and remaining on him? Had he not been the divine agent in creation, and in the illumination and inspiration of the patriarchs and prophets and seers of the old dispensation? How then could Jesus say that he "was not yet given," as the words read in our Common version? The answer to this question furnishes our best point of departure for an intelligent study of the doctrine of the Spirit. Augustine calls the day of Pentecost the "_dies natalis_" of the Holy Ghost; and for the same reason that the day when Mary "brought forth her first-born son" we name "the birthday of Jesus Christ." Yet Jesus had existed before he lay in the cradle at Bethlehem; he was "in the beginning with God"; he was the agent in creation. By him all things were. But on the day of his birth he became incarnate, that in the flesh he might fulfill his great {20} ministry as the Apostle and High Priest of our confession, manifesting God to men, and making himself an offering for the sins of the world. Not until after his birth in Bethlehem was Jesus in the world in his official capacity, in his divine ministry as mediator between man and God; and so not till after the day of Pentecost was the Holy Spirit in the world in his official sphere, as mediator between men and Christ. In the following senses then is Augustine's saying true, which calls Pentecost "the birthday of the Spirit":