(We shall give a summary of his doctrine on the Holy Spirit. PG. 33, 918-966 and 966-1012.)
The power of the Holy Spirit
1. The assisting Spirit:
There are young girls who, on the point of contracting honorable marriages or living in sumptuous palaces, renounce all for Christ. There are young men who know to how close their eyes to the beauty which lays siege to them, Christians who embrace poverty and humility. Why? Through the inspirations of the Holy Spirit. On many occasions man, through the power of the Holy Spirit with which he is endowed, manages to overcome, with a simple prayer, the untamed demons whom stout chains could not hold. . ..
God has given us, therefore, a most powerful protector and helper. He has placed at the head of his Church a wise teacher and a formidable defender. The devils are no longer to be feared, because this protector of souls overcomes them. Let us remain ever vigilant to open to him the doors of our hearts. He never tires of looking for those who are worthy of him and pours out on them his gifts.
2. The consoling Spirit:
He is also called the Paraclete and Consoler, because he consoles us and encourages us in our weakness. . . When we have to suffer a thousand insults for Christ, or see ourselves in dishonor, then is suddenly heard the voice of the Holy Spirit, who encourages us, saying: Endure it for the Lord. It is only a little that you will have to suffer now, and so much that will be given to you later. Therefore, make an effort for a while, so that you may be able to say with the angels: The sorrows of this world are not to be compared with the glory which is prepared for us. The Holy Spirit shows to men constantly the kingdom of heaven. For that reason, the martyrs, although they found themselves bodily in the presence of the judges, in spirit were transported to heaven, thus being able to mock at their torments. Do you wish to know how they could support these tortures through the power of the Spirit? The Savior said to the apostles: When they bring you to trial before synagogues, and magistrates, and officers, do not consider anxiously what you are to say, what defence to make or how to make it; the Holy Spirit will instruct you when the time comes, what words to use (Luke 12. 11-12). It is impossible to suffer martyrdom for the Lord without the aid of the Consoler. For if it is certain that no one can say the name of the Lord Jesus but by the Holy Spirit, much more certain is it that no one can give his life for Christ without him.
3. The universal distributor of God's graces:
If the omnipotent greatness of the Spirit is to be admired as he distributes his gifts among the millions of beings on this earth, and gives to each that grace which is convenient, rise up to heaven and see him there as the sanctifier of the very angels, and their perfect master.
The Holy Ghost came down from heaven to baptize the apostles and to increase their strength. The Lord had told them: There is a baptism with the Holy Spirit which you are to receive, not many days from this (Acts z. 5). They were not to receive a little grace, but the fullness of it. Just as, in the case of baptism, the water covers the one who is baptized completely, so they, on being baptized with the Holy Spirit, were completely surrounded by him. The water only touches the outside of the body, but the Spirit penetrates into every nook and corner of the soul. . .. I am going to give you another example which is evident, even if rather simple. Just as the fire, on penetrating the iron, changes it all into a fiery substance, and what was before cold metal becomes hot, what was black and dark is transformed into brilliance and light, and this is done without any obstacle, what reason is there for being surprised that the Holy Spirit can penetrate into the soul?
(Speaking of the mysterious signs which accompanied Pentecost, he says:) They received, not a destructive fire, but a salutary one, perfectly fitted to burn up the thorns of sin and change the soul into something brilliant and beautiful. The Holy Ghost rests on the heads of each one of them in the form of fire, as if to gird them with a heavenly diadem, for just as a sword of fire prevented the entrance into Paradise, so the tongues of fire, bringing the promise of salvation, will return its rights to the human race.
5. The fullness of the Spirit:
Before this coming our fathers possessed the graces necessary for salvation, but now they are poured out in abundance; before they received a share of the Holy Spirit, now on the other hand they are submerged and baptized in him.
He who was, at that moment, filled with the Holy Ghost knew well what he possessed. That is why he exclaimed: Men of Judaea, and all you are who dwelling in Jerusalem, I must tell you this; listen to what I have to say. These men are not drunk as you suppose; it is only the third hour of the day. This is what was foretold by the prophet Joel: In the last times, God says, I will pour out my spirit upon all mankind . . . (Acts 2. 14 ff.). They are drunk, but it is a drunkenness which implies death to sin and delights the heart, very different from the bodily drunkenness. This makes us forget even the things we knew; the other makes us know things which we were ignorant of before. They are drunk from having partaken of that spiritual vine of which it was said: I am the Vine, you the branches (John 15. 5).
If you wish to understand the testimony of the prophet then listen carefully to what Joel has to say: In the last times, God says, I will pour out my spirit upon all mankind. The words pour out indicate a great abundance, because God does not give his Spirit in any measure. . . . And your sons and daughters will be prophets. . . . I will pour out my spirit in those days upon my servants and hand-maids. The Holy Spirit is no respecter of persons, nor does he look for dignitaries; he looks for piety of soul. Therefore, if the rich should not be proud, neither should the poor be saddened; instead each one should prepare himself to receive the heavenly grace.