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Chapter II.

Since we are sensible that we see and hear, we cannot but be sensible that we see by sight or by some other sense; but, if we see by some other sense, then it will be perceptive of sight and colour, the subject of sight; and thus there will be either two senses for the same office, or the sight itself will be the percipient. If, besides, there is some other than the visual sense for sight, we shall have to admit an infinite series of perceptions, or else this other sense, whatever it may be, will be the visual percipient; and this might as well have been conceded to the first sense. But here there is a difficulty—if to perceive by sight is seeing, and if that which is seen is colour or something having colour, then, if any sense is to see that which sees, that sense must first have colour. It is then manifest that perception by sight is not a single perception; for even when we may not see, it is still by sight that we judge both of darkness and light, although not in the same manner. That, moreover, which sees, must have been already imbued with colour, since each sentient organ must be receptive of the object of