Leo XIII 02The doctors of the Church…say that God is present and exists in all things “by His power, in so far as all things are subject to His power; by His presence, inasmuch as all things are naked and open to His eyes; by His essence, inasmuch as he is present to all as the cause of their being” (Thomas Aquinas, Summa Theologiae 1,8,3).

But God is in man, not only as in inanimate things, but because he is more fully known and loved by him, since even by nature we spontaneously love, desire, and seek after the good.

Moreover, God by grace resides in the just soul as in a temple, in a most intimate and peculiar manner.

From this proceeds that union of affection by which the soul adheres most closely to God, more so than the friend is united to his most loving and beloved friend, and enjoys God in all fulness and sweetness.

Now this wonderful union, which is properly called “indwelling”, differing only in degree or state from that with which God beatifies the saints in heaven, although it is most certainly produced by the presence of the whole Blessed Trinity – “We will come to Him and make our abode with Him” (John 14:23.) – nevertheless is attributed in a peculiar manner to the Holy Ghost.

For, whilst traces of divine power and wisdom appear even in the wicked man, charity, which, as it were, is the special mark of the Holy Ghost, is shared in only by the just.

In harmony with this, the same Spirit is called Holy, for He, the first and supreme Love, moves souls and leads them to sanctity, which ultimately consists in the love of God.

Wherefore the apostle when calling us to the temple of God, does not expressly mention the Father or the Son, or the Holy Ghost: “Know ye not that your members are the temple of the Holy Ghost, who is in you, whom you have from God?” (1 Cor. 6:19).

Leo XIII (1810-1903): Divinum Illud Munus 9.