At least a couple pericopae come to my mind, if not to Clive Staples Lewis.
- In the context of Paul's contrast between the finite and prideful wisdom of man versus the infinite and hidden-from-the-wise wisdom of God, Paul said,
". . . but we speak . . . the wisdom which none of the rulers of this age has understood; for if they had understood it they would not have crucified the Lord of glory; but just as it is written,
'THINGS WHICH EYE HAS NOT
SEEN AND EAR HAS NOT
AND which HAVE NOT ENTERED
THE HEART OF MAN,
ALL THAT GOD HAS PREPARED
FOR THOSE WHO LOVE HIM'" (1 Corinthians 2:6-9, excerpts, NASB Updated)
Most Christians, I suspect, realize that life is a mixed bag. It has its highs and lows and lots of in-betweens. The joys of earth are mingled with sadness, trials, suffering, temptation, persecution and more. As Christians get closer to the end of their lives here on earth, they are perhaps more likely to admit that the things of earth, including happiness and pleasure, begin to pale in comparison to godly joy and true pleasure, which as the psalmist reminds us, begin now and continue forever.
"Thou wilt shew me the path of life: in thy presence is fullness of joy; at thy right hand there are pleasures for evermore" (16:11 NKJV).
Also consider the refrain from Helen H. Lemmel's hymn "Turn Your Eyes Upon Jesus":
"Turn your eyes upon Jesus,
Look full in His wonderful face,
And the things of earth will grow strangely dim,
In the light of His glory and grace" (refrain from "Turn Your Eyes Upon Jesus," by Helen H. Lemmel)
The pleasures of sin are but for a season, the writer to the Hebrews reminds us (11:25), and those pleasures, though genuinely pleasurable, eventually become alloyed with unexpected consequences, in part because of the spiritual law of reaping and sowing (Galatians 6:7 ff.)
- One of the descriptions of heaven in the Revelation of Jesus Christ:
"Then I saw a new heaven and a new earth. . . . and [God] will wipe away every tear from their eyes; and there will no longer be any death; there will no longer be any mourning, or crying, or pain; the first things have passed away" 21:1-4, excerpts, NASB Updated).
Knowing that some radical changes are coming, all of which are both good and unalloyed, causes some Christians' hearts to rejoice in hope (see Romans 5:2 KJV).
- Even what I call spiritual "mountain-top experiences" fade, sometimes quickly and sometimes more slowly, but they do fade when we leave the mountaintop (as Peter, James, and John did after Jesus' transfiguration--see John 17:1 ff.) and once again face the challenges which come our way, sometimes successfully and sometimes no so successfully (see John 17:9, 17-23).
- The Christian's hope-filled expectation of being rewarded by our Lord God for his or her God-glorifying good deeds. Jesus promised that the treasures we lay up in heaven are subject neither to devaluation and depreciation, nor can they be stolen. As the saying goes, "God is no man's debtor." One day, faithful Christians will be rewarded handsomely for their obedience to God and for their God-glorifying labors:
"[B]ut let us not lose heart in doing good; for in due time, if we do not faint, we shall reap" (Galatians 6:9 DBY).