The second omission alluded to is the Digestive Sensibility, which ought undoubtedly to be included among sensations, having all the constituents of a sense; an object--the food; a sensitive organ--the stomach; and a characteristic form of sensibility or feeling. The author farther takes notice of {6} 'Sensations of Disorganization, or of the approach to Disorganization, in any part of the body,' which too deserve to be reckoned among mental facts. He might farther have adverted to the acute and depressing feelings of the Lungs, in case of partial suffocation, with the exhilaration attending the relief from such a state, and the change from a close to a fresh atmosphere. Moreover, there are states of purely physical comfort, associated with a vigorous circulation, with healthy innervation, with the proper action of the skin; and feelings of discomfort and depression from the opposite states. A slight allusion to these various feelings occurs in chapter second towards the close. These various modes of sensibility seem to be fitly grouped together under the common head of Sensations of Organic Life: their detail being arranged according to the several organs--viz.--the Alimentary Canal, Lungs, Circulation, Nervous System, &c. These would make a sixth Sense properly so called, or a department of passive sensibility.--_B._] {7} SECTION I. SMELL. It is not material to the present purpose in what order we survey the subdivisions of this elementary class of the mental phenomena. It will be convenient to take those first, which can be most easily thought of by themselves; that is, of which a conception, free from the mixture of any extraneous ingredient, can be most certainly formed. For this reason we begin with SMELL.[2] [Bain's footnote 2: The order of exposition of the senses is not a matter of indifference. The author, like Condillac, selected Smell to begin with, as being a remarkably simple and characteristic feeling; he has found another expository advantage in it, by disturbing our routine mode of regarding the intellect as principally made up of sensations of sight. It has a startling effect on the reader, to suggest a mental life consisting wholly of smells and ideas of smell. There are two principles of arrangement of the senses, each good for its own purpose; it being understood that the active or muscular sensibility is taken apart from, and prior to, sensation proper.