❝cafe, the rule of the gospel is reversed; and it will prove, seek and you fhall not find." Agreeably to this obfervation, wit is promoted by a certain degree of intoxication, which prevents the exercise of that attention, which is neceffary for invention in matters of Science. Hence too it is, that those who have the reputation of Wits, are commonly men confident in their own powers, who allow the train of their ideas to follow in a great measure, its natural course; and hazard, in company, every thing, good or bad, that occurs to them. Men of modefty and taste seldom attempt wit in a promifcuous fociety; or if they are forced to make fuch an exertion, they are feldom fuccessful. Such men, however, in the circle of their friends, to whom they can unbofom themselves without referve, are frequently the most amufing and the most interesting of companions; aš the vivacity of their wit is tempered by a correct judgment, and refined manners; and as its effect is heightened by that fenfibility and delicacy, with which we fo rarely find it accompanied in the common intercourfe of life.

When a man of wit makes an exertion to distinguish himself, his fallies are commonly too far fetched to please. He brings his mind into a state approaching to that of the inventor, and becomes rather ingenious than witty. This is often the cafe with the writers whom Johnfon diftinguishes by the name of the Metaphysical Poets.

Those powers of invention, which neceffity occafionally calls forth in uncultivated minds, fome individuals poffefs habitually. The related ideas which, in the cafe of the former, are brought together by the flow efforts of attention and recollection, present themselves to the latter, in consequence of a more fyftematical arrangement of their knowledge. The inftantaneoufness with which fuch remote combinations are effected, fometimes appear fo wonderful,

that we are apt to afcribe it to something like infpiration; but it must be remembered, that when any fubject strongly and habitually occupies the thoughts, it gives us an intereft in the observation of the most trivial circumftance which we suspect to have any relation to it, however diftant; and by thus rendering the common objects and occurrences which the accidents of life prefent to us, fubfervient to one particular employment of the intellectual powers, establishes in the memory a connection between our favorite pursuit, and all the materials with which expe rience and reflection have supplied us for the farther profecution of it.

II. I observed, in the second place, that invention may be facilitated by general rules, which enable the inventor to direct the train of his thoughts into particular channels. Thefe rules (to afcertain which, ought to be one principal object of the logician) will afterwards fall under my confideration, when I come to examine those intellectual proceffes which are fubfervient to the discovery of truth. At prefent, I fhall confine myfelf to a few general remarks; in ftating which, I have no, other aim than to fhew, to how great a degree invention depends on cultivation and habit, even in thofe fciences in which it is generally fuppofed, that every thing depends on natural genius.

When we confider the geometrical discoveries of the ancients, in the form in which they are exhibited in the greater part of the works which have furvived to our times,it is feldom poffible for us to trace the steps by which they were led to their conclufions: and, indeed, the objects of this fcience are fo unlike those of all others, that it is not unnatural for a person who enters on the ftudy, to be dazzled by its novelty, and to form an exaggerated conception of the genius of thofe men who firft brought to light fuch a variety of truths, fo profound and fo

remote from the ordinary courfe of our fpeculations. We find, however, that even at the time when the ancient analysis was unknown to the moderns; fuch mathematicians as had attended to the progrefs of the mind in the discovery of truth, concluded a priori, that the discoveries of the Greek geometers did not, at firft, occur to them in the order in which they are stated in their writings. The prevailing opinion was, that they had been poffeffed of fome fecret method of investigation, which they carefully concealed from the world; and that they published the refult of their labors in fuch a form, as they thought would be most likely to excite the admiration of their readers. "O quam bene foret," fays Petrus Nonius, "fi qui in fcientiis mathematicis fcrip"ferint authores, fcripta reliquiffent inventa fua "eadem methodo, et per eofdem difcurfus, quibus ip"fi in ea primum inciderunt; et non, ut in mecha"nica loquitur Ariftoteles de artificibus, qui nobis "foris oftendunt fuasquas fecerint machinas, fed ar"tificium abfcondunt, ut magis appareant admirabi"les. Eft utique inventio in arte qualibet diverfa "multum a traditione: neque putandum eft pluri"mas Euclidis et Archimedis propofitiones fuiffe ab "illis ea via inventas qua nobis illi ipfas tradide"runt. The revival of the ancient analyfis, by fome late mathematicians in this country, has, in part, juftified these remarks, by fhewing to how great a degree the inventive power of the Greek geometers were aided by that method of inveftigation; and by exhibiting fome ftriking fpecimens of addrefs in the practical application of it.

The folution of problems, indeed, it may be faid, is but one mode in which mathematical invention

* See some other passages to the same purpose, quoted from different writers, by Dr. Simpson, in the preface to his Restoration of the Loci Plani of Appollonius Pergæus, Glasg. 1749.

may be displayed. The difcovery of new truths is what we chiefly admire in an original genius; and the method of analysis gives us no íatisfaction with refpect to the process by which they are obtained.

To remove this difficulty completely, by explaining all the various ways in which new theorems may be brought to light, would lead to inquiries foreign to this work. In order, however, to render the procefs of the mind, on fuch occafions, a little lefs myfterious than it is commonly fuppofed to be: it may be proper to remark, that the moft copious fource of difcoveries is the inveftigation of problems; which feldom fails (even although we should not fucceed in the attainment of the object which we have in view) to exhibit to us fome relations formerly unobferved among the quantities which are under confideration. Of fo great importance is it to concentrate the attention to a particular fubject, and to check that wandering and diffipated habit of thought, which, in the cafe of most perfons, renders their speculations barren of any profit either to themfelves or to others. Many theorems, too, have been fuggefted by analogy; many have been investigated from truths formerly known by altering or by generalifing the hypothefis; and many have been obtained by a fpecies of induction. An illuftration of thefe various proceffes of the mind would not only lead to new and curious remarks, but would contribute to diminish that blind admiration of original genius, which is one of the chief obftacles to the improvement of science.

The history of natural philosophy, before and after the time of Lord Bacon, affords another very ftriking proof, how much the powers of invention and discovery may be affifted by the ftudy of method: and in all the sciences, without exception, whoever employs his genius with a regular and habitual fuccefs, plainly fhews, that it is by means of general

rules that his inquiries are conducted. Of these rules, there may be many which the inventor never ftated to himself in words; and, perhaps, he may even be unconfcious of the affiftance which he derives from them; but their influence on his genius appears unquestionably from the uniformity with which it proceeds; and in proportion as they can be afcertained by his own fpeculations, or collected by the logician from an examination of his researches, fimilar powers of invention will be placed within the reach of other men, who apply themselves to the fame study.

The following remarks, which a truly philofophical artist has applied to painting, may be extended, with fome trifling alterations, to all the different employments of our intellectual powers.

"What we now call genius, begins, not where "rules, abftractly taken, end; but where known, "vulgar, and trite rules have no longer any place. "It must of neceffity be, that works of genius, as "well as every other effect, as it must have its caufe, "muft likewife have its rules; it cannot be by "chance, that excellencies are produced with any "conftancy, or any certainty, for this is not the na"ture of chance; but the rules by which men of "extraordinary parts, and fuch as are called men of "genius, work, are either fuch as they difcover by "their own peculiar observation, or of such a nice "texture as not easily to admit handling or expreff"ing in words.

"Unfubftantial, however, as these rules may feem, "and difficult as it may be to convey them in writing, they are ftill feen and felt in the mind of the "artift; and he works from them with as much certainty, as if they were embodied as I may fay, upon paper. It is true, these refined principles "cannot be always made palpable, like the more grofs rules of Art; yet it does not follow, but that