In 'The Great Divorce' a character asks, destraught, why she was born and a spirit replies, "for infinite joy!" Is that what CS Lewis thought the meaning of life was? Ultimate joy? Is there any other thing he said to back up this idea of what he thought? It would seem odd if such a clever, philosophical man (in my opinion) ignored the BIG 'meaning of life' question entirely!
tl;dr> NO! For Lewis, Pleasure is temporary, Joy reminds us of what is to come
First and foremost, I should admit that if the canon ever gets re-opened, The Great Divorce is my vote for book #67. :)
That said, C.S. Lewis has a very definite idea in mind when he says "Infinite Joy". In The Weight of Glory he writes:
Contrast this with mere "pleasure" when Lewis writes in Chapter 9:
Joy is the end - the purpose - of what God designed us to be. He sees joy as an "echo of heaven" which "works its way backwards into our memories." In other words, it is a reminder of the things that are to come.
As he says in The Weight of Glory (again):
This idea - that joy is an echo of heaven is more thoroughly developed here, and is often referred to as Sehnsucht.