The first, however, of the examples by which the author illustrates this law, is not marked by his usual felicity. Its shortcomings are pointed out by Mr. Bain in the preceding note. The internal feelings (says the author) which accompany indigestion, introduce trains of ideas (as in the case of horrible dreams, and of hypochondria) which are acutely painful, and may embitter the whole existence, while the sensations themselves, being comparatively of little interest, are unheeded and forgotten. It is true that the sensations in the alimentary canal, directly produced by indigestion, though (as every one knows) in some cases intense, are in others so slight as not to fix the attention, and yet may be followed by melancholy trains of thought, the connection of which with the state of the digestion may be entirely unobserved: but by far the most probable supposition appears to be, that these painful trains are not excited by the sensations, but that they and the sensations are joint or successive effects of a common organic cause. It is difficult to comprehend how these obscure sensations can excite the distressing trains of ideas by the laws of association; for what opportunity have these sensations usually had of becoming associated, either synchronously or successively, with those ideas? The explanation, in the text, of this difficulty, seems surprisingly insufficient. Anxiety, in most people, disorders the digestion; and consequently, according to the author, the sensations of indigestion excite the ideas which prevail in a state of anxiety. If that were the true explanation, the only persons with whom indigestion would depress the spirits, would be those who had suffered previous depression of spirits, sufficient in duration and intensity to disorder the digestion, and to keep it disordered long enough to effect a close and inseparable cohesion between even very slight sensations of indigestion and painful ideas excited by other causes. Surely this is not the fact. The theory has a true application in the case of the confirmed hypochondriac. When the sensations have been repeatedly experienced along with the melancholy trains of thought, a direct association is likely to grow up between the two; and when this has been effected, the first touch of the sensations may bring back in full measure the miserable mental state which had coexisted with them, thus increasing not only the frequency of its recurrence, but, by the conjunction of two exciting causes, the intensity of the misery. But the origin of the state must be looked for elsewhere, and is probably to be sought in physiology.