Here's another favorite Chesterton quote:
The Thing: Why I Am a Catholic, chap. 10 (1929).
Unless Sir Arthur Keith is very badly misreported, he specially stated that spiritual existence ceases with the physical functions; and that no medical man could conscientiously say anything else. However grave be the injury called death (which indeed is often fatal), this strikes me as a case in which it is quite unnecessary to call in a medical man at all.
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The truth is that all this business about "a medical man" is mere bluff and mystagogy. The medical man "sees" that the mind has ceased with the body. What the medical man sees is that the body can no longer kick, talk, sneeze, whistle or dance a jig. And a man does not need to be very medical in order to see that. But whether the principle of energy, that once made it kick, talk, sneeze, whistle and dance, does or does not still exist on some other plane of existence--a medical man knows no more about that than any other man. And when medical men were clear-headed, some of them (like an ex-surgeon named Thomas Henry Huxley) said they did not believe that medical men or any men could know anything about it. That is an intelligible position; but it does not seem to be Sir Arthur Keith's position. He has been put up publicly to DENY that the soul survives the body; and to make the extraordinary remark that any medical man must say the same. It is as if we were to say that any competent builder or surveyor must deny the possibility of the Fourth Dimension; because he has learnt the technical secret that a building is measured by length, breadth and height. The obvious query is--Why bring in a surveyor? Everybody knows that everything is in fact measured by three dimensions. Anybody who thinks there is a fourth dimension thinks so in spite of being well aware that things are generally measured by three. Or it is as if a man were to answer a Berkeleian metaphysician, who holds all matter to be an illusion of mind, by saying, "I can call the evidence of an intelligent navvy [laborer] who actually has to deal with solid concrete and cast iron; and he will tell you they are quite real." We should naturally answer that we do not need a navvy to tell us that solid things are solid; and it is quite in another sense that the philosopher says they are not solid. Similarly, there is nothing to make a medical man a materialist, except what might make any man a materialist.