Following up on Firor's only visit to Britain to meet Lewis earlier in 1949, Lewis explores a theme raised also in Reflections on the Psalms.
When you were here you started the subject of Praise as Worship, which has led me to some bewilderment. Take the traditional language: glorifying, i.e. literally 'making glorious' what is already not only glorious but Glory itself and the source of all other glory--magnifying what is already infinite--exalting what is already highest.--The Collected Letters of C. S. Lewis, Volume 2 (Cambridge University Press, 2004), 970-71; italics original
At first it is hard to see what all this means. It sounds like the most famous flunkeyism, like telling a rich man that he is rich: and I am sure that this impression has a powerful and repellent effect on modern people, especially in democracies. I take it the truth is that in so far as a creature sees God it cannot help in some way (not of course necessarily by words) telling Him what it sees (silence might be one way). Its 'praise' is a necessary reaction: the divine light sent back to its Source from the creature which has become its mirror. The sun is not brighter because a mirror reflects it: but the mirror is brighter because it reflects the sun.
On a lower level this necessity of telling the object what it is has been experienced by every man in love. True, he may tell the girl she is pretty in order to please her: but he'd have to tell her anyway. Thus 'exalting the Lord' is in reality indistinguishable from seeing Him. There's no question of flattery or even courtesy about it: the moment the Creator-Creature relation is normal (in the proper sense of the word normal) praise or worship is there automatically. The picture of Heaven as perpetual worship, a place, in the hideous words of the hymn
Where congregations ne'er break upwhich has tormented many a luckless child (finding one Sabbath per week a ration only too liberal!) comes alright when one sees the real meaning: the perpetual worship is the perpetual vision, the perfect exercise of all one's faculties on the perfect Object. Of that, one could never have too much.
And Sabbaths have no end