Fixing Quotes (2 quotes)
Curves that have no tangents are the rule. Those who hear of curves without tangents, or of functions without derivatives, often think at first that Nature presents no such complications. The contrary however is true. Consider, for instance, one of the white flakes that are obtained by salting a solution of soap. At a distance its contour may appear sharply defined, but as we draw nearer its sharpness disappears. The eye can no longer draw a tangent at any point. The use of a magnifying glass or microscope leaves us just as uncertain, for fresh irregularities appear every time we increase the magnification. An essential characteristic of our flake is that we suspect that any scale involves details that absolutely prohibit the fixing of a tangent.
Our model of Nature should not be like a buildinga handsome structure for the populace to admire, until in the course of time some one takes away a corner stone and the edifice comes toppling down. It should be like an engine with movable parts. We need not fix the position of any one lever; that is to be adjusted from time to time as the latest observations indicate. The aim of the theorist is to know the train of wheels which the lever sets in motionthat binding of the parts which is the soul of the engine.