An excerpt from The Everlasting Man by G. K. Chesterton

This creature was truly different from all other creatures; because he was a creator as well as a creature. Nothing in that sense could be made in any other image but the image of man. But the truth is so true that, even in the absence of any religious belief, it must be assumed in the form of some moral or metaphysical principle. In the next chapter we shall see how this principle applies to all the historical hypotheses and evolutionary ethics now in fashion; to the origins of tribal government or mythological belief. But the clearest and most convenient example to start with is this popular one of what the cave-man really did in his cave. It means that somehow or other a new thing had appeared in the cavernous night of nature, a mind that is like a mirror. It is like a mirror because it is truly a thing of reflection. It is like a mirror because in it alone all the other shapes can be seen like shining shadows in a vision. Above all, it is like a mirror because it is the only thing of its kind. Other things may resemble it or resemble each other in various ways; other things may excel it or excel each other in various ways; just as in the furniture of a room a table may be round like a mirror or a cupboard may be larger than a mirror.  But the mirror is the only thing that can contain them all. Man is the microcosm; man is the measure of all things; man is the image of God.  These are the only real lessons to be learnt in the cave, and it is time to leave it for the open road.

It will be well in this place, however, to sum up once and for all what is meant by saying that man is at once the exception to everything and the mirror and the measure of all things. But to see man as he is, it is necessary once more to keep close to that simplicity that can clear itself of accumulated clouds of sophistry.The simplest truth about man is that he is a very strange being; almost in the sense of being a stranger on the earth. In all sobriety, he has much more of the external appearance of one bringing alien habits from another land than of a mere growth of this one. He has an unfair advantage and an unfair disadvantage.  He cannot sleep in his own skin; he cannot trust his own instincts. He is at once a creator moving miraculous hands and fingers and a kind of cripple. He is wrapped in artificial bandages called clothes; he is propped on artificial crutches called furniture. His mind has the same doubtful liberties and the same wild limitations. Alone among the animals, he is shaken with the beautiful madness called laughter; as if he had caught sight of some secret in the very shape of the universe hidden from the universe itself. Alone among the animals he feels the need of averting his thought from the root realities of his own bodily being; of hiding them as in the presence of some higher possibility which creates the mystery of shame. Whether we praise these things as natural to man or abuse them as artificial in nature, they remain in the same sense unique. This is realised by the whole popular instinct called religion, until disturbed by pedants, especially the laborious pedants of the Simple Life. The most sophistical of all sophists are gymnosophists

Chesterton, G. K. The Everlasting Man. San Francisco: Ignatius Press, 1993.