because of its being too faintly marked to reproduce the old accustomed impression of the same thing. It may be a derangement of the stomach, or the liver, or the brain, such as I have experienced before, and possess a durable conception of; but being too little prominent to strike into the old track, it reminds me of nothing, and I cannot tell what it is. By-and-by, it increases somewhat, and becomes powerful enough to reinstate some likeness of it in the past, and I then recognize it. The conditions favourable to the effect are, as above stated, a great acuteness of organic sensibility, previous familiarity, and the habit of attending to organic states; together with the general power of Similarity. A keen organic sensibility may be noted as a peculiarity of some constitutions, making the individual extremely selfconscious, in the acceptation of being alive to every passing change of organic state; generating hypochondria and the alternation of fears and hopes regarding one's bodily welfare. The peculiarity will be occasionally found rising to a morbid extreme; as when the individual never passes an hour without solicitude on the matter of health and mortality. Obtuseness of feeling to what is going on within the various bodily parts is a defect fraught with dangerous neglect; while, on the other hand, a needless amount of distress, and a needless waste of precaution, may be the result of too much sensibility, whether this have its origin in the sense or in the intellect.

8. I have already cited an example from Taste. There would be no material difference in the circumstances of a case of Smell. When a very faint odour is recognized or identified, this shows that, notwithstanding the faintness of the impression, the previous sum total of the same smell has been brought back. If two persons be subjected to a particular odour, as in walking through a garden, and if one detects it while the other does not, the explanation is to be sought, as before, either in the General Power of Similarity, or in one or more of the three Special and Local circumstances— namely, greater natural delicacy or acuteness of the organ,

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greater previous familiarity with the odour, and a habit of concentrating attention upon odours in general, or this in particular. Could we ascertain that both persons had an equally acute or delicate nose, we should have to account for the difference by the two other local circumstances-greater previous familiarity, and the habit of attention, or else by the power of Similarity on the whole. If we know that two persons are equal as regards both familiarity with an odour and the habit of attending to it (circumstances tolerably easy to ascertain, and likely to go together), the greater power of identification displayed by one would either prove a special delicacy of the organ, or be referable to Similarity in general.

9. The sense of Touch does not appear to furnish any instructive case of the action of reinstatement made difficult by feebleness of impression, for we can usually command any degree of contact that we please. We may, however, derive examples in point from Hearing. It often happens that sounds are so faint as to be barely discernible, in which case we shall observe one person making them out, and another missing them. The difference of acuteness must be referred, as before, to delicacy of ear, to familiarity, acquired delicacy through the habit of attention, or else to general Similarity. The influence of familiarity, in particular, is well exemplified in sounds. Compare the hearing of our mother tongue with the hearing of a foreign tongue; every one knows how easy it is to catch up an utterance in the one, even when very faintly pronounced, and how we fail in the other under like circumstances. The same contrast is observed between a familiar voice and the voice of a stranger; persons partially deaf identify the speech of those about them, and are unable to understand others speaking at the same pitch. This fact obtains all through the field of associations by similarity; the more thoroughly accustomed the mental system is to an impression, the lighter the touch needed to make it present at any moment.

10. The same line of illustration can be carried out under the Sense of Sight. There is a point of twilight dimness

when objects begin to be doubtful; they fail to reinstate the corresponding previous impressions whereby their identity is made apparent. Haziness in the intervening sky, and mere distance, have the same effect. In those circumstances, we find that an object can be identified by one person, and not by others equally well situated for discerning it. Familiarity, together with professional habits of attention, will in many cases explain the difference, as when a sailor identifies a speck on the horizon as a ship of a particular build. Otherwise, the superiority of one person over another in discernment must be ascribed either to the sensitiveness of the eye, or to the force of similarity in general.

11. In the case of very exalted acuteness of sense, such as we witness among the Indians, who can discern the tread of horses at a great distance by applying the ear to the ground, and who have also a high degree of long-sightedness, we must refer principally to the two circumstances included in the education of the eye-familiarity and habitual concentration. It may be that natural acuteness of sense is hereditary in that state of life; still, practice is undoubtedly the main cause of the remarkable difference in this respect between these savage tribes and the generality of mankind. The education is not simply a frequent repetition of those sensations of the tramp of horses or men on the ear, but the concentration of the brain upon the sense on those occasions, whereby an intense stretch of attention habitually accompanies the act of listening. The degree of voluntary attention given to an observation of sense, will at any time make the sensation more acute; a habit of absorbing attention will generate a permanent acuteness at the expense of attention to other things. A painter will be the more impressed with a landscape that he is deaf to the song of birds, the hum of insects, or the murmur of the breeze; the whole soul, passing into one sense, aggrandizes that sense and starves the rest.

12. The acuteness of the senses in animals may in like manner be accounted for. The scent of the dog resolves

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itself into the identification of an exceedingly faint impression. An effluvium on the nostrils of a pointer, revives the former impression of the smell of a hare, while on the human nose the same effluvium is utterly devoid of effect. Here we must attribute the distinction neither to education nor to the force of the association of similarity, but to the acuteness of the smelling organ. Any given smell will produce a far more intense sensation in a dog than in a man. If we take a scent sufficiently strong to be felt by both, as when the hare is brought close enough to be felt as a smell on the human nose, the man is calm in his manifestations, whereas the dog is excited almost to madness. By this we can see, that such is the organization of the smelling organ of the dog, that impressions made on it are transmitted to the brain in a highly magnified state; and further, it may be, that the brain is specially inflammable to a particular class of sensations of smell, an effect to which nothing corresponding is found in the human constitution.

The far-sightedness of birds depends in part on the adaptation of their eyes to distant vision. It corresponds with the far-sightedness of persons habituated to remote objects, or to the change that age makes in the lenses of the human eye. We have had occasion to notice the superior development of the adapting muscles of the eye in birds, whereby the organ can go through a greater range of adjustment than is in the power of other animals.

In the examples, under the present head, we have thus brought into view, as circumstances affecting the recall of past impression by a present, a power operating generally, and three local conditions. Probably in all these instances, the special conditions are of far more importance than the general; but whether the natural or the acquired delicacy of a sense usually tells most, we do not pretend to decide.

SIMILARITY IN DIVERSITY.-SENSATIONS.

13. We now approach the case that contains the greatest amount of interesting applications-the case of similarity

disguised by mixture with foreign elements, the Like in the midst of the Unlike. There is often very great difficulty in recognizing an old familiar object owing to alterations that have been made upon it. Coming back after a lapse of years to a place where we have formerly been, we find houses and streets and fields and persons so altered that we at first fail to identify them; the differences that have overgrown the permanent features are, in many cases, such as to destroy their power of reinstating the ancient impressions. When likeness is thus surrounded with diversity, it is a doubtful point whether the attraction of similars will succeed in reviving the old by means of the new. In these cases of doubtful and difficult reinstatement, there may be observed great differences in the intellectual reach of individuals of a number of persons placed in a similar predicament, some will be struck with the likeness; the flash of identity will come over them, and the past will stand side by side with its muffled likeness in the present; others again will see no identity, the attraction of the new for the old will, in them, be overborne and quenched by the surrounding diversity.

To trace the workings of the attractive force of similarity in its struggles with the obstruction of unlike accompaniments, I count one of the most interesting problems of mental science; and I trust that, in the course of the illustration that will occupy the remainder of the present chapter, my readers will grow to be of the same opinion. Although any natural defect in this link of reproduction is perhaps less capable of being made up by artificial means than in the case of Contiguity, yet we shall see that here too there are circumstances, under our control, that aid in clearing the way for the reviving stroke of similarity.

14. Before proceeding to the main subject under the present head, namely, the Sensations, I shall advert to the one case of Action, or Movement, that furnishes interesting examples of the working of the present law, I mean articulate action, or Speech. In the numerous and various trains of articulation entering into our education in language, there