One of my favorite definitions of the Trinity comes from Mike Reeves, who says that the Trinity is the Father, Son, and Spirit loving each other forever. It is beautiful, and it is simple. And from one point of view, the claim that the one true God is the Father, Son, and Spirit is a very straightforward teaching. It is complicated only when we try to harmonize the oneness of the doctrine (“one God”) with the threeness of the doctrine (“Father, Son, and Spirit”). But the fact that we may wrestle with just how it is that God’s inner life is this way doesn’t really present a major problem. After all, why would we ever think that we as limited and finite beings would ever fully grasp any aspect of the infinite and eternal God’s inner life? “Give thanks to the Lord, call upon his name, make known his deeds among the peoples, proclaim that his name is exalted” (Isaiah 12:4).

In an effort to better grasp the truth of the Trinity, teachers through the years have proposed various analogies. As I commented on previously, the trouble with analogies is that they use material things (eggs, apples, water) to illustrate something immaterial (the nature and life of God as Father, Son, and Spirit). Inevitably these analogies end up denying the oneness of God by dividing Him into parts, or else they deny the threeness of God by reducing eternal relationships to mere roles or modes that are periodically assumed but do no exist in a relationship with each other (like me being a husband, uncle, and son-in-law).

Last week I introduced an analogy that I think may be helpful, however, and it has a very ancient pedigree. It was proposed by Augustine in the fourth century, and developed by Aquinas in the thirteenth century. It is not perfect (no analogy can be), but it opens a window for us to contemplate the Trinity.

The analogy draws upon the passages that speak of the Son and the Spirit “proceeding” from the Father (like John 8:42 and John 15:26). In my previous post in this series I discussed how the Son proceeds from the Father. By way of review, the analogy goes like this: We have minds, and thoughts proceed from those minds. But until we communicate those thoughts to others, they remain internal to us. So thinking is a kind of internal procession. John 1:1 refers to the Son as “the Word,” the logos, the idea or thought of God. In a manner similar to thoughts proceeding from our minds, the Word proceeds from God. But until the Word became flesh (John 1:14), this procession was internal, just as our thoughts remain within us until we communicate them.

The big difference between the way thoughts proceed from our mind and the way the Word proceeds from God is this – AND THIS IS CRUCIAL (so crucial I violated blog etiquette and used all caps!)! Unlike our thoughts, which are temporary – they come and go – the Bible says that the Word has always existed (John 1:1). There was never a time that the Father existed that the Son did not. The Son proceeds from the Father and always has, as Fred Sanders likes to say (The Deep Things of God, first edition, p. 93).

Through the years, this concept has come to be known as the “eternal generation” of the Son. It captures the biblical teaching that the Son derives being from the Father while at the same time being equal to the Father in the eternal divine nature (Philippians 2:6; Colossians 1:15; Hebrews 1:3). Another venerable term used to describe this teaching is “begetting,” the Father eternally begets the Son. Again – AND I CAN’T STRESS THIS ENOUGH (sorry to yell again!) – the idea here is not that the Father existed by Himself for a few billion years and then decided to have a Son. Rather, the idea here is that the Father eternally begets a Son. This is how the ancient thinkers understood the biblical descriptions of Jesus as “the only begotten God” (John 1:18 NASB).

Just as you cannot have a son without a father or a father without a son, this doctrine also means that the Father and Son are inseparable. A clumsy way to put it is that there is the Begetter, the Begotten, and the eternal begetting. A more beautiful way to put it is the prayer of Jesus, “You loved me before the foundation of the world” (John 17:24).

But what about the Holy Spirit? So far I have only discussed the relationship of the Father and the Son. Is there a related analogy for the relationship between the Father and the Spirit? There is indeed.

In addition to the procession of thoughts from the mind, there is another sort of internal procession in our experience. When I think about my wife, my heart wells up in love for her – a desire to do good for her. But until that love is expressed to her (with flowers, or jewelry, or – her most treasured way – me emptying the dishwasher!), that love remains internal to me. So just as thoughts proceed from the mind, love proceeds from the will.

Ancient thinkers like Augustine suggested that this procession of love is a good way to picture the relationship of the Spirit to the Father. The Spirit proceeds from the Father in a way similar to (but infinitely greater than) love proceeds from the will. This illustration also draws upon the passages that associate the Spirit with love, such as the coming of the Spirit upon Jesus at His baptism as the Father says, “This is my beloved Son (Matthew 3:17).

Since the word in Greek for “Spirit” (pneuma) also means “breath,” another way to think of this is that God the Father eternally breathes out the Spirit. So just as there is the eternal begetting of the Son there is the eternal breathing of the Spirit. And, just as the Father is inseparable from the Son, the Spirit is inseparable from the Father as well. Again, to spell it out rather clunkily, there is the breather, the breath, and the eternal breathing.

Fred Sanders captures these concepts in this great diagram from the first edition of The Deep Things of God, p. 92-

Are these analogies perfect? Of course not. Our thoughts do not eternally proceed from our minds, nor does love from the will. And our thoughts do not have a reciprocal relationship with our minds, but the Son does have a relationship with the Father. The same is true of the Spirit. But insofar as these analogies preserve the oneness of God while at the same time illustrating the relationships of Father, Son, and Spirit, they are probably the best that we can do.

The important thing here is to bear in mind that these analogies are conveying a beautiful truth. The Father, Son, and Spirit have always existed in the perfect unity of love. God is love, and He always has been, and always will be. Such a God is worthy of praise!