intellect, then he passeth forth to the den of memory, and bearing with him the prints of likeness, which are made in those other dens, he layeth them up in the chamber of memory. From the hindermost parts of the brain he pierceth and passeth by the marrow of the ridge bone, and cometh to the sinews of moving, that so wilful moving may be engendered, in all the parts of the nether body. Then one and the same spirit is named by divers names. For by working in the liver it is called the natural spirit, in the heart the vital spirit, and in the head, the animal spirit. We may not believe that this spirit is man's reasonable soul, but more soothly, as saith Austin, the car therof and proper instrument. For by means of such a spirit the soul is joined to the body: and without the service of such a spirit, no act the soul may perfectly exercise in the body. And therefore if these spirits be impaired, or let of their working in any work, the accord of the body and soul is resolved, the reasonable spirit is let of all its works in the body. As it is seen in them that be amazed, and mad men and frantic, and in others that oft lose use of reason. The sight is most simple, for it is fiery, and knoweth suddenly things that be full far. The sight is shapen in this manner. In the middle of the eye, that is, the black thereof, is a certain humour most pure and clear. The philosophers call it crystalloid, for it taketh suddenly divers forms and shapes of colours as crystal doth. The sight is a wit of perceiving and knowing of colours, figures, and shapes, and outer properties. Then to make the sight perfect, these things are needful, that is to wit, the cause efficient, the limb of the eye convenient to the thing that shall be seen, the air that bringeth the likeness to the eye, and taking heed, and easy moving. The cause efficient is that virtue that is called animal. The instrument and limb is the humour like crystal in either eye clear and round. It is clear that by the clearness thereof the eye may beshine the spirit, and air; it is round that it be stronger to withstand griefs. The outer thing helping to work, is the air, without which being a means, the sight may not be perfect. It needeth to take heed, for if the soul be occupied about other things than longeth to the sight, the sight is the less perfect. For it deemeth not of the thing that is seen. And easy moving is needful, for if the thing that is seen moveth too swiftly, the sight is cumbered and disparcled with too swift and continual moving: as it is in an oar that seemeth broken in the water, through the swift moving of the water. In three manners the sight is made. One manner by straight lines, upon the which the likeness of the thing that is seen, cometh to the sight. Another manner, upon lines rebounded again: when the likeness of a thing cometh therefrom to a shewer, and is bent, and re-boundeth from the shewer to the sight. The third manner is by