自然之母難道給了這隻動物所有感覺的泉源，卻不容許牠有感覺？~~伏爾泰

多可悲啊，是如何貧乏的心靈，才會說動物是沒有理解力與感情的一種機器…

How pitiful, and what poverty of mind, to have said that the animals are machines deprived of understanding and feeling…

（以評價你自己的方式）想一想，若有一隻狗，失去主人，到處尋覓，一路上悲慘哀嚎，回到屋裏仍焦躁無法平靜，樓上樓下這房間那房間到處找，最後終於在書房找到心愛的主人，又叫又跳，磨蹭不停，顯得很興奮。牠比人類更懂得什麼是友情，但有些野蠻人卻把牠抓走，釘在桌子上，活生生將之解剖，目的只是為了讓你看看這狗的血管與神經。

但你會發現，原來牠有著所有你也都有的感覺器官。那麼，說動物是機械論者，請告訴我，自然之母難道給了這隻動物所有感覺的泉源，卻不容許牠有感覺？難道牠有神經，卻感受不到痛苦？

Judge (in the same way as you would judge your own) the behaviour of a dog who has lost his master, who has searched for him in the road barking miserably, who has come back to the house restless and anxious, who has run upstairs and down, from room to room, and who has found the beloved master at last in his study, and then shown his joy by barks, bounds and caresses. There are some barbarians who will take this dog, that so greatly excels man in capacity for friendship, who will nail him to a table and dissect him alive, in order to show you his veins and nerves. And what you then discover in him are all the same organs of sensation that you have in yourself. Answer me, mechanist, has Nature arranged all the springs of feeling in this animal to the end that he might not feel? Has he nerves that he may be incapable of suffering?

伏爾泰，法國思想家，1694-1778；摘自其著作《哲學字典》，Philosophical Dictionary.