“For with [God] were always present the Word and Wisdom, the Son and the Spirit, by Whom and in Whom, freely and spontaneously, He made all things, to Whom also He speaks, saying, ‘Let Us make man after Our image and likeness’.” St. Irenaeus (2^nd-3rd centuries)

“There is one God, the Father of the living Word, Who is His subsistent Wisdom and Power and Eternal Image: perfect Begetter of the perfect Begotten, Father of the only-begotten Son. There is one Lord, Only of the Only, God of God, Image and Likeness of Deity, Efficient Word, Wisdom comprehensive of the constitution of all things, and Power formative of the whole creation, true Son of true Father, Invisible of Invisible, and Incorruptible of Incorruptible, and Immortal of Immortal, and Eternal of Eternal. And there is One Holy Spirit, having His subsistence from God, and being made manifest by the Son to men: Image of the Son, Perfect Image of the Perfect; Life, the Cause of the living; Holy Fount; Sanctity, the Supplier, or Leader, of Sanctification; in Whom is manifested God the Father, Who is above all and in all, and God the Son, Who is through all. There is a perfect Trinity, in glory and eternity and sovereignty, neither divided nor estranged.” St. Gregory Thaumaturgus (3^rd century)

“To us there is One God, for the Godhead is One, and all that proceeds from Him is referred to One, though we believe in Three Persons. For one is not more and another less God; nor is One before and another after; nor are They divided in will or parted in power; nor can you find here any of the qualities of divisible things; but the Godhead is, to speak concisely, undivided in separate Persons; and there is one mingling of Light, as it were of three suns joined to each other.” St. Gregory of Nazianzen (4^th century, Doctor of the Church)

“They ought to confess that the Father is God, the Son God, and the Holy Spirit God, as they have been taught by the divine words, and by those who have understood them in their highest sense.” St. Basil the Great (4^th century, Doctor of the Church)

“He who has the Spirit not only is called Christ’s, but even has Christ Himself. For it cannot but be that where the Spirit is, there Christ is also. For wheresoever one Person of the Trinity is, there the whole Trinity is present. For It is undivided in Itself, and has a most entire Oneness.” St. John Chrysostom (4^th-5^th centuries, Doctor of the Church)

“And it is by thought that He creates, and thought is the basis of the work, the Word filling it and the Spirit perfecting it.” St. John of Damascus (7^th-8^th centuries, Doctor of the Church)

“The Father begets the Son, and the Spirit proceeds from the Father and the Son. In these few words the mystery of the life of the Trinity is enshrined, as well as every perfection that exists in creation, which is nothing other than a multifarious echo, a hymn of praise in multi-colored polyphony, of that First Most Beautiful Mystery…Who is the Father? In what does His essence consist? That of giving birth, for He gives birth to the Son before all ages and for all ages He gives birth to Him…The Father begets, the Son is begotten, the Spirit is conceived: such is the Essence of the Persons distinct among themselves.” St. Maximilian Kolbe (19th-20^th centuries)

“The Father loves the Son and the Son loves the Father. Love is not in one alone.; love is not in the other. The love that we have for one another is not just in me and not just in you. Love is always a bond between two or among several. That is why even lovers will speak of our love, something outside of the lovers themselves. So love is not in the Father, love is not in the Son, love is the mysterious bond uniting both. Because we are here dealing with the infinite, that divine love is so deep, so profound that it cannot express itself by canticles, words, or embraces. It can express itself only by that which signifies the fullness and exhaustion of all giving, namely, a sigh. Something that’s too deep for words. That is why the bond of love between the Father and the Son is called the Holy Breath, the Holy Spirit. As the three angles of the triangle do not make three triangles, but one, so there are three persons or three relationships in God, but only one God.” Ven. Fulton Sheen (19^th-20^th centuries)

“The Descent of the Holy Ghost Upon the Apostles. Many have wished that Our Blessed Lord had remained on earth, that we might have heard His voice, seen His compassionate eyes, and brought our children to be blessed by His hands. But He said ‘I can say truly that it is better for you I should go away; He Who is to befriend you will not come to you unless I do go, but if only I make my way there, I will send Him to you.’ If our Lord remained on earth, He would have been only a symbol to be copied – not a life to be lived. By returning to his heavenly Father, He could then send both from the Father and Himself the Holy Spirit that would make Him live on earth in His new Body, which is the Church.” Ven. Fulton Sheen

“The Holy Spirit as Love and Gift comes down, in a certain sense, into the very heart of the sacrifice which is offered on the Cross. Referring here to the biblical tradition we can say: He consumes this sacrifice with the fire of the love which unites the Son with the Father in the Trinitarian communion. And since the sacrifice of the Cross is an act proper to Christ, also in this sacrifice He ‘receives’ the Holy Spirit. He receives the Holy Spirit in such a way that afterwards – and He alone with God the Father – can ‘give Him’ to the Apostles, to the Church, to humanity.” Pope St. John Paul II (20^th-21st centuries)