8 Consequently, we too receive the Holy Ghost if we love the Church, if we are joined together by charity, if we rejoice in the Catholic name and faith. Let us believe, brethren; as much as every man loves the Church of Christ, so much has he the Holy Ghost. For the Spirit is given, as the apostle says, “to manifestation.” To what manifestation? Just as the same apostle says, “For to one is given by the Spirit the word of wisdom, to another the word of knowledge after the same Spirit, to another faith in the same Spirit, to another the gift of healing in one Spirit, to another the working of miracles in the same Spirit.” For there are many gifts given to manifestation, but thou, it may be, hast nothing of all those I have said.
If you love, it is not nothing that you have: if you love unity, whoever has anything in that unity has it also for you. Take away envy, and what I have is yours too. The envious temper puts men apart, soundness of mind unites them. In the body, the eye alone sees; but is it for itself alone that the eye sees? It sees both for the hand and the foot, and for all the other members. If a blow be coming against the foot, the eye does not turn away from it, so as not to take precaution.
Again, in the body, the hand alone works, but is it for itself alone the hand works? For the eye also it works: for if a coming blow comes, not against the hand, but only against the face, does the hand say, I will not move, because it is not coming to me? So the foot by walking serves all the members: all the other members are silent, and the tongue speaks for all. We have therefore the Holy Spirit if we love the Church; but we love the Church if we stand firm in its union and charity.
For the apostle himself, after he had said that diverse gifts were bestowed on diverse men, just as the offices of the several members, says, “Yet I show you a still more pre-eminent way;” and begins to speak of charity. This he put before tongues of men and angels, before miracles of faith, before knowledge and prophecy, before even that great work of mercy by which a man distributes to the poor all that he possesses; and, lastly, put it before even the martyrdom of the body: before all these so great things he put charity.
Have it, and you shall have all: for without it, whatever you can have will profit nothing. But that you may know that the charity of which we are speaking refers to the Holy Spirit (for the question now in hand in the Gospel is concerning the Holy Spirit), hear the apostle when he says, “The charity of God is shed abroad in our hearts by the Holy Spirit which is given to us.”
Source: Tractates on the Gospel of John (New Advent)