The human body as a mechanism is far from perfect. It can be beaten or surpassed at almost every point by some product of the machine-shop or some animal. It does almost nothing perfectly or with absolute precision. As Huxley most unexpectedly remarked a score of years ago, "If a manufacturer of optical instruments were to hand us for laboratory use an instrument so full of defects and imperfections as the human eye, we should promptly decline to accept it and return it to him. But," as he went on to say, "while the eye is inaccurate as a microscope, imperfect as a telescope, crude.
