Some answered, that they did not remove the book to lesson the light, but to receive more rays, and let all the space between the letters and their eyes be filled with lightsome air. Others agreed with those that imagine the rays of vision mix with one another; for since there is a cone stretched between each eye and the object, whose point is in the eye and whose basis is the object, it is probable that for some way each cone extends apart and by itself; but, when the distance increases, they mix and make but one common light; and therefore every object appears single and not two, though it is seen by both eyes at once; for the conjunction of the cones makes these two appearances but one. These things supposed, when old men hold the letters close to their eyes, the cones not being joined, but each apart and by itself, their sight is weak; but when they remove it farther, the two lights being mingled and increased, see better, as a man with both hands can hold that for which either singly is too weak. But my brother Lamprias, though unacquainted with Hieronymus's notions, gave us another reason. We see, said he, some species that come from the object to the eye, which at their first rise are thick and great; and therefore when near disturb old men, whose eyes are stiff and not easily penetrated; but when they are separated and diffused into the air, the thick obstructing parts are easily removed, and the subtile remainders coming to the eye gently and easily slide into the pores; and so the disturbance being less, the sight is more vigorous and clear. Thus a rose smells most fragrant at a distance; but if you bring it near the nose, it is not so pure and delightful; and the reason is this,--many earthy disturbing particles are carried with the smell, and spoil the fragrancy when near, but in a longer passage those are lost, and the pure brisk odor, by reason of its subtility, reaches and acts upon the sense.