Good Infection

Big idea

Summary

Lewis opens with the image of two books stacked on a table, one resting on the other, to show that a cause need not exist 'before' its effect in time even though it produces that effect; if the books had rested that way forever, the lower book's support would still be the cause of the upper book's position without ever having preceded it. He applies this directly to the Father-Son relationship: the Father is the source of the Son, but there was never a time before the Son existed, since begetting, unlike ordinary human fatherhood, is an eternal, simultaneous act.

He reinforces this with a second analogy, the way an act of imagining and the mental picture it produces begin and end at the same instant, and describes the Son as the eternal 'self-expression' of the Father, compared to light streaming from a lamp or heat from a fire, while cautioning that these images inevitably fall short of the biblical language of Father and Son, to which one should always return.

The chapter's theological center is the claim that 'God is love,' which Lewis insists requires more than one Person within God, since love is inherently relational and a solitary being could not have been loving before anything else existed to love. He argues that the relationship of love between Father and Son is itself so real and unified that it constitutes a third Person, the Holy Spirit, illustrating this with the shared 'spirit' or character that emerges when people join together in a family, club, or team.

Lewis closes with the practical payoff: divine life is not a prize God might arbitrarily hand out, but something caught by proximity, the way warmth is caught by standing near a fire, so that humanity's whole calling is to be drawn into this three-personal life of love. He states plainly that the entire purpose of becoming a Christian is to share in Christ's own eternal life and, in his phrase, to become 'a little Christ.'

Key points

• Uses the 'two books' thought experiment to show that a cause can be eternal and simultaneous with its effect, rather than necessarily preceding it in time.
• Explains the Father-Son relationship as a timeless act of begetting, or eternal self-expression, rather than a sequence like ordinary human fatherhood.
• Argues that 'God is love' logically requires a plurality of Persons within God, since love needs both a lover and a beloved.
• Presents the Holy Spirit as the real, personal 'spirit' of shared love that arises from the Father-Son relationship, comparable to (but more real than) a family or team's shared character.
• Describes divine life as something caught by nearness or participation, using the image of infection, rather than a prize distributed externally.
• States that the entire purpose of the Christian life is to share in Christ's own begotten life and to become, in effect, 'a little Christ.'

Illustrations & analogies

• Lewis imagines two books stacked forever, one resting on the other, to show how a cause can be eternal and simultaneous with, rather than prior to, its effect.
• He compares the act of imagining something to the mental picture it produces, both beginning and ending together, as a further picture of timeless cause and effect.
• He compares the Son's eternal origin from the Father to light streaming from a lamp or heat radiating from a fire.
• He points to the shared 'spirit' that develops in a family, club, or trade union as a faint, impersonal echo of the far more real personal union that is the Holy Spirit, and compares receiving divine life itself to standing near a fire to get warm, since proximity, not arbitrary award, is what brings the effect.

Notable lines

Love is something that one person has for another person.

C. S. Lewis Book IV, Ch. 4 — Good Infection

Every Christian is to become a little Christ.

C. S. Lewis Book IV, Ch. 4 — Good Infection

Good things as well as bad, you know, are caught by a kind of infection.

C. S. Lewis Book IV, Ch. 4 — Good Infection

Related Scripture

• 1 John 4:8

For reflection and discussion

1. What does the claim 'God is love' require about God's own inner nature, according to Lewis, and why couldn't a solitary being always have been 'love'?
2. How does the 'good infection' image shape your understanding of how someone actually receives spiritual life, rather than earning it or being handed it as a prize?
3. What do you think it would practically look like for you to 'become a little Christ,' in Lewis's phrase?