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away with them the total impression of a building, a picture, or a poem; for instead of being acquisitions de novo, they are merely variations of effects already engrained on the artist's

recollection.

To whatever extent one thing is the repetition of another, the cost of contiguous acquisition is saved. But it is necessary that the repetition or identity should be perceived; in other words, the new lesson must reinstate, by the force of similarity, all the previous trains that in any way correspond with it. An old acquirement containing many steps in common with a lesson in hand, will be of no use unless it is recalled; should the disagreeing points be so marked as to cloud the resemblance and stifle the identifying action, nothing is gained by the agreement. It consequently happens that a mind feeble as regards the restoring force of similarity, misses the help that past acquirements could often bring to bear upon present effects; whereas a remarkable energy of recal will make everything available that contains the smallest trace of common matter.

47. To take a few examples from Science. The subject matter of Geometry embodies a few fundamental notions and processes. A definition, an axiom, a postulate, a proposition, whether theorem or problem, a chain of demonstration, are to the beginner things absolutely new. They must be fixed by the plastic power of Contiguity, and time and concentration must be allowed for the purpose. But in a good head, one or two examples of each strongly imprinted will make all the rest easy; the method or character of the devices will be seen through and acquired, and in every new case the mind will fall back upon the old ones for the common element, and concentrate attention on the points of difference solely. When, after going over a few definitions, the mind gets impressed with the form and peculiarity of a definition, there is little to acquire in the rest; a slight substitution serves to make a new one out of an old; the definition of a square is easily changed to suit a rectangle. So with an axiom: the first is the most laborious to acquire; every subsequent one is easier than the preceding. When we come to the propositions, there is a

very great deal of novelty at first; the whole scheme and management of a theorem or problem-the formality in the statement, and in the order of the proof-are things utterly strange to the young beginner; to acquire a simple proposition is a heavy strain upon his adhesiveness for abstract and representative forms. When this first acquisition is made, it can be turned to account in every succeeding proposition, provided the operation of similarity is not obstructed by the differences that encumber the new cases. Indeed, if each step in the machinery of Geometry were, without much waste of time, firmly learned on the first encounter, and if the reviving power of similarity for this class of things were unfailing, one's progress through Euclid would be a race, such as is recorded of Pascal and Newton. But to the generality of minds identities in geometrical reasoning are hard to perceive; a difference in collaterals utterly extinguishes the sense of a similarity in substance, and every new proposition is a fresh labour, as if nothing like it had been gone through before.

What is true of Geometry holds in all the sciences. There is in each one a vast deal of repetition both of the facts, or subject-matter, and of the formal machinery, although with great differences of mode and circumstance. The law of gravitation runs through all Astronomy; and in the deepest calculations of the celestial movements the same mathematical devices are constantly reproduced in new complications. A mind that can seize a calculation once for all, and trace it out in the thickest envelope of diversity, will speedily pass through the intricacies of this vast subject, or of any other abstract science. Along with the grasp of similarity that can suffice to trace out identities hitherto passed over by all former minds working in the same sphere, it is to be presumed that the more ordinary resemblances will be easy to strike; hence an original mind in science is also distinguished for the rapidity of its course along the track of the already known. Much of the acquisitions of a strong intellect is in reality the re-discovery of what is already known; such an intellect catches the identities of abstraction, classification, induction, deductive application, and demonstrative reasoning, even before they are pointed

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out by the master. He will make but a poor mathematician that needs to refer to his book for the demonstration of every successive theorem. With all branches of Physics, with Chemistry and Physiology, the very same remarks will apply. It is the nature of an advanced science to contain innumerable identifications summed up in its definitions and general laws; it was by a vigorous similarity that these were first formed; by the same power they are rapidly acquired.

So in the more concrete sciences of the Natural History group. In Zoology, Botany, Mineralogy, Geology, there has been accumulated a fund of identities in the classifications made of the objects of each. To acquire these classifications the learner must himself feel the similarity among the individuals; and if his mind is of that powerful kind that can trace many of the likenesses by its own unassisted force, he will speedily string together all the groups that have been formed by others. It is of consequence to a botanist looking to a new plant that he shall be able to recal at once whatever other plants he had known that in any way resemble it; he will in this way both determine its true class, and stamp it with ease, upon his memory.

48. In all the acquisitions of Business, no less than of Science, similarity will likewise bear an important part. If an apprentice at the Law has that deep and subtle identifying power that sees in every new case whatever similarity there is in it to some previous one, he saves half his labour; his mind breaks in upon the old track, and on that builds up the new recollection to the extent of the likeness. It is possible to lay under contribution in this way matters quite different from the subject in hand; to clench the technicalities of the law we may go back upon recollections out of all sciences and arts, illustrating the subject as it were to one's self. The mind of Lord Bacon could see in anything that presented itself multifarious analogies to things the most remote; these analogies he could produce to his readers to facilitate their conception. of his meaning, and by the same power he could shorten his own labour and study. When a clever person surprises us by instantaneously comprehending and firmly retaining some new

method of procedure, we may be quite sure that it has taken hold of him by resuscitating something analogous out of the storehouses of his past experience; whenever this easy comprehension and this permanent retention form part of the mental character, and show themselves in a wide range of subjects, a vigorous identifying faculty certainly lies at the

bottom.

49. The case of the Artistic mind presents no essential difference. The storing up of impressions of objects of art is easiest when the identifying power is so strong as to bring up on every occasion whatever resembles the object before the view. That a likeness should exist between something we are at present looking at or listening to, and some past impressions of the eye or the ear, and that that likeness should not be felt, is a misfortune, a loss in every way, and for this reason among others, that to impress the new object on the memory we require as much repetition and pains as if nothing of the kind had ever been experienced before. In reading a poem the memory is assisted to remember it by all the similarities of thought, of imagery, of language, of metre and rhythm, that it is able to evoke from the traces of former readings and recollections. In a mind very keen and susceptible on all these poetic elements, and having the power of similarity highly manifested, almost every touch will rouse up something from the past that has a certain degree of resemblance, and that something will be an already formed recollection to eke out the retentiveness of the new strain. The more one's acquisitions advance, the greater the scope of this work of fitting old cloth into new garments; but previous acquisition is only of avail according as the stroke of resuscitation is good, and able to pierce the disguises of diversity and altered form that may attach to the most resembling of all our past examples.

The contiguous retentiveness of the mind is put to the fullest test only by entire and absolute novelty, a thing that is more and more rare as one grows older. In learning languages, for example, we have less to acquire with every new individual language. Latin prepares for French, Italian, Spanish, &c.; German for Dutch; Sanscrit for Hindostanee.

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The generalizations of philologists in tracing common roots through all the Indo-European tongues, greatly diminish the number of original ties that contiguity has to fix. All discoveries of generalization have this effect; and if an individual learner can see likenesses in addition to what have been generally promulgated, his labour is shortened by strokes of power peculiar to himself.

50. The Historical Memory might furnish good examples of the intervention of Similarity in making up the coherent tissue of recollected events. In the transactions of the world, great and small, there is so much of repetition, that a new history is in reality a various reading of some old one; not to mention how much each nation repeats itself through its successive epochs. To a dull mind a great deal of this repetition is lost for all purposes, the aid to memory among the rest; but a keen-sighted attraction for every vestige of recurring likeness enables another person to retain large masses of narrative at a small expense of adhesive acquisition. Campaign suggests campaign, and one battle another; an intrigue, a negociation, a career of ambition, a conquest, a revolution, are no new things to the student gone some way in history; certain minor features, some of the proportions and circumstantials, are special to the case in hand, and these must be fixed in the memory by pure contiguity. No man could recite a narrative of any sort from a single reading or hearing, if it were all new to him; to tell a story an hour after getting it from another party would be impossible but for our possessing already among our stored recollections more than nineteentwentieths of all the adhesions that enter into it.