In Hearing, the mode of action is touch or mechanical contact. In the remaining senses, the contact is accompanied with other forces. Taste and Smell involve chemical change, as well as contact. The action of Light on the eye is probably some species of molecular disturbance involving chemical action. This mode of viewing the order and dependence of the senses belongs more especially to the theory of the development of the organic system, which is made prominent in the Psychology of Mr. Herbert Spencer. The arrangement might be variously expressed:--it might be Touch, Hearing, Sight, Taste, Smell, Organic Sensibility; or Touch, Hearing, Taste, Smell, Organic Sensibility, Sight.--_B._] {8} In the Smell three things are commonly distinguished. There is the ORGAN, there is the SENSATION, and there is the antecedent of the Sensation, the {9} external OBJECT, as it is commonly denominated,[1*] to which the Sensation is referred as an effect to its cause. [Mill's footnote 1: It is necessary here to observe, that I use, throughout this Inquiry, the language most commonly in use. This is attended with its disadvantages; for on the subject of mind the ordinary language almost always involves more or less of theory, which may or may not appear to me to correspond with the true exposition of the phenomena. The advantages, however, of not departing from familiar terms still appeared to me to preponderate; and I am willing to hope, that such erroneous suggestions, as are sometimes inseparable from the language I have thought it best upon the whole to employ, will be corrected, without any particular notice, by the analysis which I shall present.--(_Author's Note_.)] These three distinguishable particulars are common to all the five Senses. With regard to the ORGAN, which is a physical rather than a mental subject of inquiry, I shall have occasion to say little more than is required to make my reader distinguish, with sufficient accuracy, the part of his body to which the {10} separate feelings of his five Senses belong. And with regard to the antecedent of the Sensation, or OBJECT of the Senses, the proper place for explaining what is capable of being known of it is at a subsequent part of this inquiry. My desire at present is, to fix the attention of the reader upon the SENSATION; that he may mark it as a mental state of a particular kind, distinct from every other feeling of his nature. The ORGAN of Smell, as every body knows, is situated in the mouth and nostrils, or in the nerves, appropriated to smelling, which are found in the passage between the mouth and nostrils, and in the vicinity of that passage.