that a ray is an accidental quality or mode, and furthermore seeing that that body which is other than the eye will not fail, in its turn, of being, either, _firstly_, sent out from the eye, in which case it will follow as a matter of course that the eye will not see all that is beneath the clear blue of the sky, since one body will not penetrate throughout the whole of another body, unless forsooth it moves the latter away and occupies its place; and even should the disputer plead a vacuum, not only does Plato deny the existence of a vacuum utterly, but also if we accomodatingly yield this point and admit the existence of a vacuum, yet for all this the body that goes forth from the eye will penetrate throughout the body of water, for example, into such of its pores as are empty only, and not into the whole of the water’s bulk; so that even according to this opinion it will necessarily so be that the eye will see only some places of all that is under water;--or else, _secondly_, that body which is other than the eye will not fail of being an intervening body intermediate between the seer and the seen, in which case the light[I] which comes forth from the eye will subsist through it; nevertheless this opinion too is unsound, for the reason that every thing whatsoever is, in proximity to its source, so much the stronger, and in this respect light has not its equal; whence it follows as regards the object seen that, however closely and nearly it approaches to the eye, our perception will then be stronger; and thus if we do away with the intermediary body, the eye will still perceive the object felt by its sense of sight, and thus the intermediary which is the vehicle and carrier of light is no longer needed, save accidentally (by chance); and then too there is no need, in order to see, for an exit of light: this too is a falsehood. Wherefore Plato’s opinion is worthless. As for such as hold that the perceiver of the thing seen is the imaginative power itself through the imprinting of the form (image) of the sensible object upon it, these render the absent on the same footing as the present, since in the imaginative power there may exist the image of a sensible object, notwithstanding the absence afterwards of the object that had been so felt: at which time however the living being so preserving that image will not be qualified with sight but with imagination and memory. Furthermore these theorists (opiners) make a greater blunder still, seeing that they render a thing of Nature’s make and composition wholly idle, useless, and unneeded in the operation of visual perception; inasmuch as in their opinion the imaginative power itself meets immediately sensible objects, and thus spares Nature the task of adapting an instrument (organ), to wit the complex eye.