But why is He first given to the disciples on earth, and afterwards sent from heaven? Because there are two commandments of love, to love God, and to love our neighbour. The spirit to love our neighbour is given on earth, the spirit to love God is given from heaven. As then love is one, and there are two commandments; so the Spirit is one, and there are two gifts of the Spirit. And the first is given by our Lord while yet upon earth, the second from heaven, because by the love of our neighbour we learn how to arrive at the love of God.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: Hom. xxvi.