Let us suppose that a man, born deaf should deny the reality of sounds, because his ears were never sensible of them. To convince him of his error, I place a violin before his eyes; and, by playing on another, concealed from him, give a vibration to the strings of the former. This motion, I tell him, is effected by sound.
“Not at all,” says he, “the cause of the vibration of the string, is in the string itself: it is a common quality in all bodies so to vibrate.”
“Show me then,” I reply, “the same vibration in other bodies; or at least, the cause of it in this "string.”
“I cannot,” the deaf man may reply, “but wherefore must I, because I do not conceive how this string vibrates, attribute the cause to your pretended sounds, of which I cannot entertain the least idea? This would be to attempt an explanation of one obscurity by another still greater. Either make your sounds perceptible to me, or I shall continue to doubt their existence.”
The more I reflect on our capacity of thinking, and the nature of the human understanding, the greater is the resemblance I find between the arguments of our materialists and that of such a deaf man. They are, in effect, equally deaf to that internal voice which, nevertheless, calls to them so loud and emphatically. A mere machine is evidently incapable of thinking, it has neither motion nor figure productive of reflection: whereas in man there exists something perpetually prone to expand, and to burst the fetters by which it is confined. Space itself affords not bounds to the human mind: the whole universe is
