“ARE you serious?—do you really believe that a machine thinks?” I got no immediate reply; Moxon was apparently intent upon the coals in the grate, touching them deftly here and there with the fire-poker till they signified a sense of his attention by a brighter glow. For several weeks I had been observing in him a growing habit of delay in answering even the most trivial of commonplace questions. His air, however, was that of preoccupation rather than deliberation: one might have said that he had “something on his mind.” Presently he said: “What is a ‘machine’? The word has been variously defined. Here is one definition from a popular dictionary: ‘Any instrument or organization by which power is applied and made effective, or a desired effect produced.’ Well, then, is not a man a machine? And you will admit that he thinks—or thinks he thinks.” “If you do not wish to answer my question,” I said, rather testily, “why not say so?—all that you say is mere evasion. You know well enough that when I say ‘machine’ I do not mean a man, but something that man has made and controls.” “When it does not control him,” he said, rising abruptly and looking out of a window, whence nothing was visible in the blackness of a stormy night. A moment later he turned about and with a smile said: “I beg your pardon; I had no thought of evasion. I considered the dictionary man’s unconscious testimony suggestive and worth something in the discussion. I can give your question a direct answer easily enough: I do believe that a machine thinks about the work that it is doing.” That was direct enough, certainly. It was not altogether pleasing, for it tended to confirm a sad suspicion that Moxon’s devotion to study and work in his machine-shop had not been good for him. I knew, for one thing, that he suffered from insomnia, and that is no light affliction. Had it affected his mind? His reply to my question seemed to me then evidence that it had; perhaps I should think differently about it now. I was younger then, and among the blessings that are not denied to youth is ignorance. Incited by that great stimulant to controversy, I said: “And what, pray, does it think with—in the absence of a brain?” The reply, coming with less than his customary delay, took his favorite form of counter-interrogation: “With what does a plant think—in the absence of a brain?” “Ah, plants also belong to the philosopher class! I should be pleased to know some of their conclusions; you may omit the premises.”