虽然动物会思考也会学习，可是却不能像人那样，对学会的事物作出任何真正的改革。每种鸟都有自己的筑巢方法，但总是用的同样的方式，互相之间也不学习。可是，你知道，人类就不是这样，人类总是要寻求新的盖房子的方式，人类总是要改进做一些事情的方式方法。
Many of the things that animals know how to do they seem to know either without learning, or in some way which we cannot understand. They are said to do such things by instinct; but no one can tell what instinct is. It is by this instinct that birds build their nests and beavers their dams and huts. If these things were all planned and thought out just as men plan new houses, there would be some changes in the fashions of them, and some improvements.
有许多事情，似乎是动物都知道怎么做。它们秘书科不用学就会或者是用我们还没了解到的方法就掌握了。据说它们都是凭着本能去做这类事情，都能像人类设计新房子那样，动物也能有周密的计划和仔细的考虑，那么动物的巢穴在式样上也会有所变化和改进的。
I have spoken of the building instinct of beavers. An English gentleman caught a young one and put him at first in a cage. After a while he let him out in a room where there was a great variety of things. As soon as he was let out he began to exercise his building instinct. He gathered together whatever he could find, brushes, baskets, boots, clothes, sticks, bits of coal, etc., and arranged them as if to build a dam. Now, if he had had his wits about him, he would have known that there was no use in building a dam where there was no water.
我提到了河狸的建筑上的本能。一位英国先生抓到了只小河狸，起先把它放到一只笼子里了，过了一会儿又把它放出来，放进了一间里面有很多种不同的东西的房间里。刚把这只小河狸放出来，它就开始施展了它筑坝的本能。它把凡是能找到的东西：刷子、筐子、靴子、衣服、棍子、煤块等等都集中到一起，然后来安排这些东西，好像要筑水坝似的。那么，如果它真的有头有脑的话，它就该知道，在这没有水的地方筑水坝是根本没用的。
It is plain that, while animals learn about things by their senses as we do, they do not think nearly as much about what they learn, and this is the reason why they do not improve more rapidly. Even the wisest of them, as the elephant and the dog, do not think very much about what they see and hear. Nor is this all. There are some things that we understand, but about which animals know nothing. They have no knowledge of anything that happens outside of their own observation. Their minds are so much unlike ours that they do not know the difference between right and wrong.
道理很明显，当动物像我们人一样在凭各种感官学习事物时，动物对所学的事物几乎不多加考虑，这就是之所以动物不能较迅速地提高的原因。即使是像大象和小狗这样最聪明的动物，也不能对它们的所见所闻加以思考。事情还远不止如此。有些事情我们能懂，而这些事情，动物根本一窍不通。动物对于发生在自己的视野之外一切事物一无所知。动物的头脑与我们人类的头脑是很不相同的，所以动物的头脑就分辨不出真伪或对错。
