“The false religion of lust is baser than the false religion of mother-love or patriotism or art: but lust is less likely to be made into a religion.”

“Poetry most often communicates emotions, not directly, but by creating imaginatively the grounds for those emotions. It therefore communicates something more than the emotion; only by means of that something more does it communicate the emotion at all.”

“The Moral Law isn't any one instinct or any set of instincts: it is something which makes a kind of tune (the tune we call goodness or right conduct) by directing the instincts. (...) The most dangerous thing you can do is to take any one impulse of your own nature and set it up as the thing you ought to follow at all costs. There's not one of them which won't make us into devils if we set it up as an absolute guide. You might think love of humanity in general was safe, but it isn't. If you leave out justice you'll find yourself breaking agreements and faking evidence in trials 'for the sake of humanity,' and become in the end a cruel and treacherous man.”

“A sum can be put right: but only by going back till you find the error and working it afresh from that point, never by simply going on.”

“You may have noticed that the books you really love are bound together by a secret thread. You know very well what is the common quality that makes you love them, though you cannot put it into words: but most of your friends do not see it at all, and often wonder why, liking this, you should also like that. Again, you have stood before some landscape, which seems to embody what you have been looking for all your life; and then turned to the friend at your side who appears to be seeing what you saw -- but at the first words a gulf yawns between you, and you realise that this landscape means something totally different to him, that he is pursuing an alien vision and cares nothing for the ineffable suggestion by which you are transported. Even in your hobbies, has there not always been some secret attraction which the others are curiously ignorant of -- something, not to be identified with, but always on the verge of breaking through, the smell of cut wood in the workshop or the clap-clap of water against the boat's side? Are not all lifelong friendships born at the moment when at last you meet another human being who has some inkling (but faint and uncertain even in the best) of that something which you were born desiring, and which, beneath the flux of other desires and in all the momentary silences between the louder passions, night and day, year by year, from childhood to old age, you are looking for, watching for, listening for? You have never had it. All the things that have ever deeply possessed your soul have been but hints of it -- tantalising glimpses, promises never quite fulfilled, echoes that died away just as they caught your ear. But if it should really become manifest -- if there ever came an echo that did not die away but swelled into the sound itself -- you would know it. Beyond all possibility of doubt you would say "Here at last is the thing I was made for". We cannot tell each other about it. It is the secret signature of each soul, the incommunicable and unappeasable want, the thing we desired before we met our wives or made our friends or chose our work, and which we shall still desire on our deathbeds, when the mind no longer knows wife or friend or work. While we are, this is. If we lose this, we lose all.”

“Every age has its own outlook. It is specially good at seeing certain truths and specially liable to make certain mistakes. We all, therefore, need the books that will correct the characteristic mistake of our own period. And that means the old books.”

“Can a mortal ask questions which God finds unanswerable? Quite easily, I should think. All nonsense questions are unanswerable. How many hours are in a mile? Is yellow square or round? Probably half the questions we ask - half our great theological and metaphysical problems - are like that.”

“It is easy to acknowledge, but almost impossible to realize for long, that we are mirrors whose brightness, if we are bright, is wholly derived from the sun that shines upon us.”

“Onward and Upward! To Narnia and the North!”

“The most valuable thing the Psalms do for me is to express the same delight in God which made David dance.”

“In writing. Don't use adjectives which merely tell us how you want us to feel about the thing you are describing. I mean, instead of telling us a thing was "terrible," describe it so that we'll be terrified. Don't say it was "delightful"; make us say "delightful" when we've read the description. You see, all those words (horrifying, wonderful, hideous, exquisite) are only like saying to your readers, "Please will you do my job for me."

“As for all I can tell, the only difference is that what many see we call a real thing, and what only one sees we call a dream.”

“A moderated religion is as good for us as no religion at all—and more amusing.” 

“Friendship, then, like the other natural loves, is unable to save itself. In reality, because it is spiritual and therefore faces a subtler enemy, it must, even more wholeheartedly than they, invoke the divine protection if it hopes to remain sweet. For consider how narrow its true path is. Is must not become what the people call a "mutual admiration society"; yet if it is not full of mutual admiration, of Appreciative love, it is not Friendship at all.”

“Life is too deep for words, so don't try to describe it, just live it. Actually this quote doesn't sound like C.S. Lewis at all. Can anyone provide a source?”