it 'patient thought,' to attain the highest construction that is attainable in the case. This is the moral or volitional property of constructiveness, which I pointed out at the outset, as entering along with the properly intellectual forces into the constructive faculty. The power of patient thought, when highly developed, must repose upon a strong congeniality of mind towards the subject in hand, a passion or fascination for the peculiar class of ideas concerned, such that these ideas can be detained and dwelt upon without costing effort. The mathematical mind in addition to its intellectual aptitude for retaining and recovering mathematical forms, should have this congenial liking for these forms, in order to prepare it for original discovery. The number of trials necessary to arrive at a new construction is commonly so great, that without a positive affection or fascination for the subject we would inevitably grow weary of the task. The patient thought of the naturalist, desirous of rising to new classifications, must repose on the liking for the subject, which makes it to him a sweet morsel rolled under the tongue, and gives an enjoyment even to the most fruitless endeavours. This is the emotional condition of originality of mind in any department. When Napoleon described himself as un homme politique,' we are to interpret the expression as implying a man of the political fibre or grain, a character whose charm of existence was the handling of political combinations, so that his mind could dwell with ease in this region of ideas.

6

18. What has been said above, with reference to the Abstractive process of science, applies also to Induction, or the generalizing of propositions, or truths. This may be either a simple effort of the reproductive force of similarity, or there may be wanted a constructive process in addition. In generalizing the law of the bending of light in passing from one medium to another, Snell constructed a proposition by bringing in a foreign element, namely, the geometrical sines of the angles: he found that the degree of bending was as the sine of the inclination of the ray. This is a good example of the devices required to attain to a general law, and a mind well versed in such foreign elements, apt to revive them, and

INDUCTION-DEDUCTION.

595

disposed to dwell upon them, will be the most likely to succeed in the happy fetches and combinations that clench great principles of science.

19. In the processes of Deduction, by which general laws and principles are applied to the clearing up of particular cases and the solving of problems, the same line of remark might be pursued. The mind being prepared beforehand with the principles most likely for the purpose, and having a vigorous power of similarity in that region, incubates in patient thought over the problem, trying and rejecting, until at last the proper elements come together in the view, and fall into their places in a fitting combination.

The vast structure of the mathematical sciences is a striking example of constructiveness, as distinguished from the discoveries of mere identification through the law of similarity. In Geometry, in Algebra, in the higher Calculus, and in the endless devices of refined analysis, we see an apparatus perfectly unprecedented, the result of a long series of artificial constructions for the working out of particular ends. It would not be difficult to trace out the course of this creative energy; the mental forces involved in it being no other than those that we have been endeavouring to explain.

20. In the devices of Experimental science there comes into play a constructiveness, akin to invention in the arts and manufactures. The air-pump, for example, is an illustrious piece of constructive ingenuity. The machine already in use for pumping water had to be changed and adapted to suit the case of air; and it was necessary that some one well versed in mechanical expedients, and able to recal them on slight hints of contiguity or similarity, should go through the tedious course of trials that such a case required.

PRACTICAL CONSTRUCTIONS.

21. The region of inventions for the practical ends of life might be traversed for illustrations of constructive genius. Likewise the department of administrative capacity in every

class of affairs and every kind of business might be explored with the same view.

Not one of the leading mental peculiarities above laid down as applicable to scientific constructiveness can be dispensed with in the constructions of practice;—the intellectual store of ideas applicable to the special department; the powerful action of the associating forces; a very clear perception of the eud, in other words, sound judgment; and, lastly, that patient thought, which is properly an entranced devotion of the energies to the subject in hand, rendering application to it spontaneous and easy.

In the case of originality in all departments, whether science, practice, or fine art, there is a point of character that is worth specifying in this place, as being more obviously of value in practical inventions and in the conduct of business and affairs, I mean an active turn, or a profuseness of energy put forth in trials of all kinds on the chance of making lucky hits. In science, meditation and speculation can often do much, but in practice, a disposition to try experiments is of the greatest service. Nothing less than a fanaticism of experimentation could have given birth to some of our grandest practical combinations. The great discovery of Daguerre, for example, could not have been regularly worked out by any systematic and orderly research; there was no way but to stumble on it, so unlikely and remote were the actions brought together in one consecutive process. The discovery is unaccountable until we learn that the author had been devoting himself to experiments for improving the diorama, and thereby got deeply involved in trials and operations far remote from the beaten paths of inquiry. The fanaticism that prompts to endless attempts was found in a surprising degree in Kepler. A similar untiring energy-the union of an active temperament with intense fascination for his subject-appears in the character of Sir William Herschel. When these two attributes are conjoined; when profuse active vigour is let loose on a field which has an unceasing charm for the mind, we then see human nature surpassing itself; and, with the aid of adequate intellectual power, the very highest results may be anticipated.

The greatest practical inventions being so much dependent upon chance, the only hope of success is to multiply the chances by multiplying the experiments.

The invention of Daguerre* illustrates-by a modern instance the probable method whereby some of the most ancient inventions were arrived at. The inventions of the scarlet dye, of glass, of soap, of gunpowder, could have come only by accident; but the accident in most of them would probably fall into the hands of men who had been engaged in extensive trials with the constituted materials. Intense application, days of watching, nights of waking,'-in all likelihood attended ancient discoveries as well as modern. In the historical instances we know this to have been the case. The mental absorption of Archimedes is a proverb.

22. The present topic furnishes a good opportunity for singling out for more special notice the quality of mind well known by the name of Judgment. I have already included a clear perception of the end to be served, as essential to a high order of constructive ingenuity, simply because without this, though there may be a great profusion of the requisite devices and suggestions towards the required combination, the fitting result is really not arrived at. Some combination short of the exigencies of the case is acquiesced in, and the matter

rests.

The various regions of practice differ very much in respect of the explicitness of the signs of success. In some things there is no doubt at all; we all know when we have made a good dinner, when our clothing is warm, or when a wound has healed. The miller knows when there is water enough for his mill, and the trader knows when he has found out a good market. The end in those cases is so clear and explicit

The wonderful part of this discovery consists in the succession of processes that had to concur in one operation before any eflect could arise. Having taken a silver plate, iodine is first used to coat the surface; the surface is then exposed to the light, but the effect produced is not apparent till the plate has been immersed in the vapour of mercury. To light upon such a combination, without any clue derived from previous knowledge, an innumerable series of fruitless trials must have been gone through.

that no one is deluded into the notion of having compassed it, if this is really not the case. But in more complex affairs, where perfect success is unattainable, there is room for doubts as to the degree actually arrived at. Thus in public administration, we look only for doing good in a considerable majority of instances, and it is often easy to take a minority for a majority in such a case. So in acting upon human beings, as in the arts of teaching, advising, directing, we may suffer ourselves to fall into a very lax judgment of what we have actually achieved, and may thus rest satisfied with easy exertions and flimsily put together devices. A sound judgment, meaning a clear and precise perception of what is really effected by the contrivances made use of, is to be looked upon as the first requisite of the practical man. He He may be meagre in intellectual resources, he may be slow in getting forward and putting together the appropriate devices, but if his perception of the end is unfaltering and strong he will do no mischief and practise no quackery. He may have to wait long in order to bring together the apposite machinery, but when he has done so to the satisfaction of his own thorough judgment, the success will be above dispute. Judgment is in general more important than fertility, because a man by consulting others and studying what has been already done, may usually obtain suggestions enough, but if his judgment of the end is loose, the highest exuberance of intellect is only a

snare.

The adapting of one's views and plans to the opinions of others is an interesting case of constructiveness, and would illustrate all the difficulties that ever belong to the operation. A more abundant intellectual suggestiveness is requisite according as the conditions of the combination are multiplied; we must transform our plan into a new one containing all the essentials of success, with the addition that it must conform to the plan of some other person. There is in that case a considerable amount of moral effort, as well as of intellectual adaptation; the giving way to other men's views being by no means indifferent to our own feelings.

The subject of Speech in general would present some