They may arise, from memory or imagination, as readily as from perception; but when they arise from memory or imagination, they are as truly distinguishable from what we remember and imagine, as they are distinguishable from our perceptions of mere forms and colours and other sensible qualities, when they arise from what we perceive. To have arranged all the varieties of feelings of which the mind is susceptible, in the three great divisions to which our arrangement as yet has extended,--though it is unquestionably to have made some advance in our generalization,--is yet to have made only a small part of the necessary progress; since each of these three orders comprehends almost innumerable phenomena, which require the aid of more minute division. In the class of our external affections, indeed, this subdivision is very simple and easy; since our separate organs of sense furnish, of themselves, a very evident ground of distinction. But the two orders of our internal affections have no such obvious and tangible distinction, to serve as the basis of their subdivisions. They admit, however,--as I trust we shall find,--of distinctions, which, though not equally _obvious_, are almost equally definite, and require only a very little reflection, to be understood as clearly, as the organic relations, according to which we distinguish our sensations of sound, or smell, or sight. It is not my intention, however, to proceed, at present, to the consideration of these subdivisions; since the nature of the more minute arrangement will, I conceive, be better understood, when we come to treat of each separate order fully, than they could be now, by the mere enumeration of a few names, of the propriety of which, as mere names, and, still more of the propriety of the arrangement which they involve, you could not be expected to form any accurate judgment, without a fuller elucidation.