[Editor's footnote 4: In the case of hearing, as of smell, one of the ambiguities brought to notice by the author is of questionable reality. It is doubtful if "hearing" is ever used as a name of the organ. To the question supposed in the text, "by which of my organs do I have the knowledge of sound" the correct answer would surely be, not "my hearing"--an expression which, so {20} applied, could only be accepted as elliptical,--but "my organ of hearing," or (still better) "my ear." Again, the phrase "I have the sense of hearing" signifies that I have a capacity of hearing, and that this capacity is classed as one of sense, or in other words, that the feelings to which it has reference belong to the class Sensations: but the organ, though a necessary condition of my having the sensations, does not seem to be implied in the name.--_Ed._] {21} SECTION III. SIGHT. In SIGHT, the organ is very conspicuous, and has an appropriate name, the Eye. In ordinary language, the object of sight is the body which is said to be seen. This is a similar error to those which we have detected in the vulgar language relating to the senses of smell and hearing. It is Light alone which enters the eye; and Light, with its numerous modifications, is the sole object on sight. How the particles of light affect the nerves of the eye, in the peculiar manner in which they are affected in sight, without affecting the other nerves of the body, in any similar manner, we can render no account. That the feeling we have in sight, is very different from the feeling we have in hearing, in smelling, in tasting, or touching, every man knows. It is difficult, however, to detach the feeling we have in sight from every other feeling; because there are other feelings which we are constantly in the habit of connecting with it; and the passage in the mind from the one to the other is so rapid, that they run together, and can not easily be distinguished. The different modifications of light we call colour. But we cannot think of the sensation of colour, without at the same time {22} thinking of something coloured, of surface or extension, a notion derived from another sense. That the feelings of sight which we are capable of distinguishing from one another, are exceedingly numerous, is obvious from this, that it is by them we distinguish the infinite variety of visible objects. We have the sensation; the sensation suggests the object; and it is only by the difference of sensation, that the difference of object can be indicated. Some of the things suggested by the sensations of sight, as extension and figure, are suggested so instantaneously, that they appear to be objects of sight, things actually seen. But this important law of our nature, by which so many things appear to be seen, which are only suggested by the feelings of sight, it requires the knowledge of other elements of the mental phenomena to explain.