We’re asked to imagine two books, one lying on top of the other. The bottom book, book A, is supporting the top book, book B. Imagine, also, that books A and B have always been lying in such a position, and that A’s position did not exist before B had its position on top of A. Lewis will return to this analogy in a moment.
The gist of Lewis’s analogy is that it’s possible for book A to “hold up” book B without having been there before book B—a good approximation for the relationship between God and Christ.
In an earlier chapter, Lewis tried to argue that God was a being who contained three beings (the Holy Trinity). But it is difficult to define God as such without implying that one of the beings was there before the others—indeed, our words for God and Christ, the “Father” and the “Son,” clearly suggest that God came “before” Christ.
Lewis will spend a few chapters dissecting the Holy Trinity: the Christian concept that God consists of three beings, God, Christ, and the Holy Spirit. It’s worth noting that not all Christian denominations believe in the Holy Trinity; Unitarians, notably, worship only one unified God.
Lewis now returns to books A and B. Sometimes, when we speak of a cause and an effect, we make the mistake of assuming that the cause originates before the effect. But in fact, cause and effect often occur simultaneously. When we imagine something, for example (like the two books in this analogy), the act of imagining doesn’t come before the mental picture we see in our minds; on the contrary, the cause and the effect occur simultaneously. The same is true of the relationship between God and Christ: God is the cause of Christ, but there was never a point in time when God existed and Christ did not.
Here, Lewis’s argument parallels the writings of the American pragmatists John Dewey and William James: cause and effect, contrary to our intuition, often occur in the same instant. But just as a cause is more “basic” and “fundamental” than its corresponding effect (i.e., it would seem that you can have a cause without an effect, but not an effect without a cause), God is more fundamental than Christ, even if God and Christ have been in existence for the same period of time.
One of the defining features of Christianity is that it defines God as a “dynamic, pulsating activity” as well as a person. Lewis suggests that, while God and Christ are definite beings, the relationship between God and Christ is also a person. Such an idea, Lewis admits, sounds very strange, but perhaps God and Christ’s relationship is like the “spirit” of a family or a club; a strong, intimate connection. The connection between Christ and God, the Holy Ghost, is the third of the three beings in the Holy Trinity. It is harder to speak of the Holy Ghost than Christ or God, because the Holy Ghost resembles a process more than a person. The Holy Ghost “acts” through us, more than it appears before us; it is the state of love and closeness between the Father and the Son.
Lewis defines the Holy Ghost as the “link” between God and Christ. Strictly speaking, the Holy Ghost often refers to the spirit of God present in the world in the time between Christ’s resurrection and the Final Judgment; however, Lewis (following Christian doctrine on the subject), also characterizes the Holy Ghost as the personified relationship between God and Christ—and, perhaps, between all human beings.
The Holy Trinity unites the Father, Son, and Holy Ghost in a kind of “dance.” The only way to achieve lasting peace is to get close to the three aspects of the Trinity—“once a man is separated from God, what can he do but wither and die?” If we worship God, however, we will win the gift of zoe, a Christ-like spiritual life.
The analogy of a “dance” is significant because it suggests that worshipping God is a constant process, rather than a rigid, unchanging status quo. The passage also foreshadows Lewis’s analysis of zoe, the spiritual life awaiting human beings in Heaven.