made them has kindled in them I know not what celestial flame, the like of which all the rest of nature does not afford. These eyes are a sort of looking-glasses, wherein all the objects of the whole world are painted by turns and without confusion in the bottom of the retina that the thinking part of man may see them in those looking-glasses. But though we perceive all objects by a double organ, yet we never see the objects double, because the two nerves that are subservient to sight in our eyes are but two branches that unite in one pipe, as the two glasses of a pair of spectacles unite in the upper part that joins them together. The two eyes are adorned with two equal eyebrows, and, that they may open and close, they are wrapped up with lids edged with hair that defend so delicate a part. SECT. XXXIX. Of the Forehead and Other Parts of the Face. The forehead gives majesty and gracefulness to all the face, and serves to heighten all its features. Were it not for the nose, which is placed in the middle, the whole face would look flat and deformed, of which they are fully convinced who have happened to see men in whom that part of the face is mutilated. It is placed just above the mouth, that it may the more easily discern, by the odours, whatever is most proper to feed man. The two nostrils serve at once both for the respiration and smell. Look upon the lips: their lively colour, freshness, figure, seat, and proportion, with the other features, render the face most beautiful. The mouth, by the correspondence of its motions with those of the eyes, animates, gladdens, suddens, softens, or troubles the face, and by sensible marks expresses every passion. The lips not only open to receive food, but by their suppleness and the variety of their motions serve likewise to vary the sounds that form speech. When they open they discover a double row of teeth with which the mouth is adorned. These teeth are little bones set in order in the two jaw-bones, which have a spring to open and another to shut in such a manner that the teeth grind, like a mill, the aliments in order to prepare their digestion. But these aliments thus ground go down into the stomach, through a pipe different from that through which we breathe, and these two pipes, though so neighbouring, have nothing common. SECT. XL. Of the Tongue and Teeth.