[Editor's footnote 28: If it be admitted that in the three cases here specified the word vividness, as applied to our impressions, has a definite meaning, it seems to follow that this meaning may be extended in the way of analogy, to other cases than these. There are, for example, sensations which differ from some other sensations like fainter feelings of the same kind, in much the same manner as the idea of a sensation differs from the sensation itself: and we may, by extension, call these sensations less vivid. Again, one idea may differ from another idea in the same sort of way in which the idea of a sensation had long ago differs from that of a similar sensation received recently: that is, it is a more faded copy--its colours and its outlines are more effaced: this idea may fairly be said to be less vivid than the other. The author himself, a few pages farther on, speaks of some complex ideas as being more "obscure" than others, merely on account of their greater complexity. Obscurity, indeed, in this case, means a different quality from the absence of vividness, but a quality fully as indefinite. Mr. Bain, whose view of the subject will be found further on, draws a fundamental distinction (already indicated in a former note) between the attributes which belong to a sensation regarded in an intellectual point of view, as a portion of our knowledge, and those which belong to the element of Feeling contained in it; Feeling being here taken in the narrower acceptation of the word, that in which Feeling is opposed to Intellect or Thought. To sensations in their intellectual aspect Mr. Bain considers the term vividness to be inapplicable: they can only be distinct or indistinct. He reserves the word vividness to express the degree of intensity of the sensation, considered in what may be called its emotional aspect, whether of pleasure, of pain, or of mere excitement. Whether we accept this restriction or not, it is in any case certain, that the property of producing a strong and durable association without the aid of repetition, belongs principally to our pleasures and pains. The more intense the pain or pleasure, the more promptly and powerfully does it associate itself with its accompanying circumstances, even with those which are only accidentally present. In the cases mentioned in the text, a single occurrence of the painful sensation is sufficient to produce an association, which neither time can wear out nor counter-associations dissolve, between the idea of the pain and the ideas of the sensations which casually accompanied it in that one instance, however intrinsically indifferent these may be.--_Ed._]