Only two animals have entered the human household otherwise than as prisoners and become domesticated by other means than those of enforce servitude (束缚): the dog and the cat. Two things they have in common, namely, that both belong to the order of carnivores and both serve man in their capacity of hunters. In all other characteristics, above all in the manner of their association with man, they are as different as the night from the day. There is no domestic animal which has so rapidly altered its whole way of living, indeed its whole sphere of interests, that has become domestic in so true a sense as the dog; and there is no animal that, in the course of its century-old association with man, has altered so little as the cat. There is some truth in the assertion that the cat, with the exception of a few luxury breeds, such as Angoras, Persians and Siamese, is no domestic animal but a completely wild being. Maintaining its full independence, it has taken up its abode in the house and outhouses of man, for the reason that there are more mice there than elsewhere. The whole charm of the dog lies in the depth of the friendship and the strength of the spiritual ties with which he has bound himself to man, but the appeal of the cat lies in the very fact that she has formed no close bond with him, that she has the uncompromising independence of a tiger or a leopard while she is hunting in his stables and barns; that she still remains mysterious and remote when she is rubbing herself gently against the leg of her mistress or purring contentedly in front of the fire. I should no more like to be without a cat in my home than to be without the dog that trots behind me in field or street. Since my earliest youth I have always had dogs and cats about me. Business-like friends have advised me to write a dog-book and a cat-book separately, because dog-lovers dislike cats and cat-lovers frequently abhor dogs. But I consider it the finest test of genuine love and understanding of animals if a person has sympathies for both these creatures, and can appreciate in each its own special virtue. The passage concludes that________.