SCEPTICISM OF THE INSTRUMENT
Let me endeavour to make myself a little less obscure by a most flagrant instance from physical things. Suppose someone began to talk seriously of a Man seeing an atom through a microscope, or better perhaps of cutting one in half with a knife. There are a number of non-analytical people who would be quite prepared to believe that an atom could be visible to the eye or cut in this manner. But anyone at all conversant with physical conceptions would almost as soon think of killing the square root of 2 with a rook rifle as of cutting an atom in half with a knife. Our conception of an atom is reached through a process of hypothesis and analysis, and in the world of atoms there are no knives and no men to cut. If you have thought with a strong consistent mental movement, then when you have thought of your atom under the knife blade, your knife blade has itself become a cloud of swinging grouped atoms, and your microscope lens a little universe of oscillatory and vibratory molecules. If you think of the universe, thinking at the level of atoms, there is neither knife to cut, scale to weigh nor eye to see. The universe at that plane to which the mind of the molecular physicist descends has none of the shapes or forms of our common life whatever. This hand with which I write is in the universe of molecular physics a cloud of warring atoms and molecules, combining and recombining, colliding, rotating, flying hither and thither in the universal atmosphere of ether.
You see, I hope, what I mean when I say that the universe of molecular physics is at a different level from the universe of common experience;—what we
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