The Who Quotes (page 213)
There was a man who sat each day looking out through a narrow vertical opening where a single board had been removed from a tall wooden fence. Each day a wild ass of the desert passed outside the fence and across the narrow opening—first the nose, then the head, the forelegs, the long brown back, the hindlegs, and lastly the tail. One day, the man leaped to his feet with the light of discovery in his eyes and he shouted for all who could hear him: “It is obvious! The nose causes the tail!
Frank Herbert
When two members of a family or two intimate friends are separated, and one goes abroad and one remains at home, the return of the relative or friend who has been travelling always seems to place the relative or friend who has been staying at home at a painful disadvantage when the two first meet. The sudden encounter of the new thoughts and new habits eagerly gained in the one case, with the old thoughts and old habits passively preserved in the other, seems at first to part the sympathies...
Wilkie Collins