How does anyone know that he has received the Holy Spirit? Let him question his own heart: if he loves his brother, then Gods Spirit remains in him. Let him see; let him prove himself before the eyes of God; let him see if he has love for peace and unity, love for the Church spread throughout the world. Let him not consider only love of the brother or sister he sees before him; there are many others whom we do not see but to whom we are joined in the unity of the Spirit.... We are in one body; we have one head in heaven. Our eyes dont see each other; its as if they dont know each other. But in the charity of the bodys frame do they not know each other? When they're both open, the right eye doesn't look at something that the left eye doesn't see. Send a glance from your right eye without the left, if you can. They both go out together, are directed the same way; their aim is one though their places are distinct. If, then, all who with you love God and have the same intention as you, dont focus on your physical separation. The eyesight of your hearts you have fixed on the light of truth. If you wish to know, therefore, that you have received the Spirit, ask your heart whether perhaps you have the sacrament but not do not have the power of the sacrament. Ask your heart, and if love of a brother is there, rest secure. There cannot be love without Gods Spirit, because Paul cries out: The love of God is poured out in our hearts by the Holy Spirit that has been given to us. (Augustine on I John, Hom. 6, 11; PL 35, 2025-2026)