In the preface of Orthodoxy, Chesterton sets forth the whole book as an attempt to explain the strange ways in which the world is both our home, and not our home. How can the world provide both the comfort of security and the excitement of adventure? He writes:
“This at least seems to me the main problem for philosophers, and is in a manner the main problem of this book. How can we contrive to be at once astonished at the world and yet at home in it? How can this queer cosmic town, with its many-legged citizens, with its monstrous and ancient lamps, how can this world give us at once the fascination of a strange town and the comfort and honour of being our own town?”
At the end of chapter 5, Chesterton explains how Christianity answered this question for him:
The Christian optimism is based on the fact that we do not fit in to the world. I had tried to be happy by telling myself that man is an animal, like any other which sought its meat from God. But now I really was happy, for I had learnt that man is a monstrosity. I had been right in feeling all things as odd, for I myself was at once worse and better than all things. The optimist’s pleasure was prosaic, for it dwelt on the naturalness of everything; the Christian pleasure was poetic, for it dwelt on the unnaturalness of everything in the light of the supernatural. The modern philosopher had told me again and again that I was in the right place, and I had still felt depressed even in acquiescence. But I had heard that I was in the wrong place, and my soul sang for joy, like a bird in spring. The knowledge found out and illuminated forgotten chambers in the dark house of infancy. I knew now why grass had always seemed to me as queer as the green beard of a giant, and why I could feel homesick at home.