mena and laws of moving bodies; and to indulge themselves in conjectures about the efficient causes of motion, and the nature of those minds, by which they conceived the particles of matter to be animated; and that they so often blended the history of facts with their metaphysical speculations. In the present state of science, indeed, we are not liable to such mistakes in natural philosophy; but it would be difficult to mention any other branch of knowledge which is entirely exempted from them. In metaphysics, I might almost say they are at the bottom of all our controversies. In the celebrated dispute, for example, which has been so long carried on about the explanation given by the ideal theory of the phenomena of perception, the whole difficulty arose from this, that philosophers had no precise notion of the point they wished to ascertain; and now that the controversy has been brought to a conclusion, (as I think all men of candour must confess it to have been by Dr. Reid,) it will be found, that his doctrine on the subject throws no light whatever on what was generally understood to be the great object of inquiry,—I mean, on the mode of communication between the mind and the material world; and, in truth, amounts only to a precise description of the fact, stripped of all hypothesis, and stated in such a manner as to give us a distinct view of the insurmountable limits which nature has in this instance prescribed to our curiosity. The same observation may be made, on the reasonings of this sensible and original author, with respect to some metaphysical questions that had been started on the subject of vision; in particular, concerning the cause of our seeing objects single with two eyes, and our seeing objects erect, by means of inverted images on the retina.

If we were to examine, in like manner, the present state of morals, of jurisprudence, of politics, and of philosophical criticism, I believe we should find, that the principal circumstance which retards their progress, is the vague and indistinct idea which those who apply to the study of them have formed to themselves of the objects of their researches. Were these objects once clearly defined, and the proper plan of inquiry for

attaining them illustrated by a few unexceptionable models, writers of inferior genius would be enabled to employ their industry to much more advantage, and would be prevented from adding to that rubbish which, in consequence of the illdirected ingenuity of our predecessors, obstructs our progress in the pursuit of truth.

As a philosophical system of logic would assist us in our particular scientific investigations, by keeping steadily in our view the attainable objects of human curiosity; so, by exhibiting to us the relation in which they all stand to each other, and the relation which they all bear to what ought to be their common aim, the advancement of human happiness, it would have a tendency to confine industry and genius to inquiries which are of real practical utility; and would communicate a dignity to the most subordinate pursuits, which are in any respect subservient to so important a purpose. When our views are limited to one particular science, to which we have been led to devote ourselves by taste or by accident, the course of our studies. resembles the progress of a traveller through an unexplored country; whose wanderings from place to place are determined merely by the impulse of occasional curiosity, and whose opportunities of information must necessarily be limited to the objects which accidentally present themselves to his notice. It is the philosophy of the mind alone which, by furnishing us with a general map of the field of human knowledge, can enable us to proceed with steadiness, and in a useful direction; and while it gratifies our curiosity and animates our exertions, by exhibiting to us all the various bearings of our journey, can conduct us to those eminences from whence the eye may wander over the vast and unexplored regions of science. Lord Bacon was the first person who took this comprehensive view of the different departments of study, and who pointed out, to all the classes of literary men, the great end to which their labours should conspire,—the multiplication of the sources of human enjoyment, and the extension of man's dominion over nature. Had this object been kept steadily in view by his followers, their discoveries, numerous and important as they have been, would have

advanced with still greater rapidity, and would have had a much more extensive influence on the practical arts of life.1

From such a system of logic, too, important assistance might be expected, for reforming the established plan of public or academical education. It is melancholy to reflect on the manner in which this is carried on in most, perhaps I might say in all the countries of Europe; and that, in an age of comparative light and liberality, the intellectual and moral characters of youth should continue to be formed on a plan devised by men who were not only strangers to the business of the world, but who felt themselves interested in opposing the progress of useful knowledge.

For accomplishing a reformation in the plan of academical study, on rational and systematical principles, it is necessary, in the first place, to consider the relation in which the different branches of literature, and the different arts and sciences, stand to each other, and to the practical purposes of life and secondly, to consider them in relation to the human mind, in order to determine the arrangement best fitted for unfolding and maturing its faculties. Many valuable hints towards such a work may be collected from Lord Bacon's writings.

II. Another very important branch of a rational system of logic (as I had occasion already to observe) ought to be: to lay down the rules of investigation which it is proper to follow in the different sciences. In all of these, the faculties of the understanding are the instruments with which we operate; and

1 ["Alius error est, quod post singulas. scientias et artes suas in classes distributas, mox a plerisque universali rerum cognitioni et philosophiæ primæ renunciatur; quod quidem profectui doctrinarum inimicissimum est. Prospectationes fiunt e turribus, aut locis præaltis; et impossibile est, ut quis exploret remotiores interioresque scientiæ alicujus partes, si stet super plano ejusdem scientiæ, neque altioris scientiæ veluti speculum conscendat."] . . .

"Omnium autem gravissimus error in deviatione ab ultimo doctrinarum fine

consistit. Appetunt enim homines scientiam, alii ex insitâ curiositate et irrequieta; alii animi causâ et delectationis, alii existimationis gratiâ; alii contentionis ergo, atque ut in disserendo superiores sint plerique propter lucrum et victum paucissimi, ut donum rationis, divinitus datum, in usus humani generis impendant. Hoc enim illud est, quod revera doctrinam atque artes condecoraret, et attoleret, si contemplatio, et actio, arctiore quam adhuc vinculo copularentur."-De Aug. Scient. lib. i.

without a previous knowledge of their nature, it is impossible to employ them to the best advantage. In every exercise of our reasoning and of our inventive powers, there are general laws which regulate the progress of the mind; and when once these laws are ascertained, they enable us to speculate and to invent, for the future, with more system, and with a greater certainty of success. In the mechanical arts, it is well known how much time and ingenuity are misapplied by those who acquire their practical skill by their own trials, undirected by the precepts or example of others. What we call the rules of an art, are merely a collection of general observations, suggested by long experience, with respect to the most compendious and effectual means of performing every different step of the processes which the art involves. In consequence of such rules, the artist is enabled to command the same success in all his operations, for which the unskilled workman must trust to a happy combination of accidental circumstances; the misapplications, too, of the labour of one race are saved to the next; and the acquisition of practical address is facilitated, by confining its exertions to one direction. The analogy is perfect in those processes which are purely intellectual, and to regulate which is the great object of logic. In the case of individuals. who have no other guide to direct them in their inquiries than their own natural sagacity, much time and ingenuity must inevitably be thrown away in every exertion of the inventive powers. In proportion, however, to the degree of their experience and observation, the number of these misapplications will diminish; and the power of invention will be enabled to proceed with more certainty and steadiness to its object. The misfortune is, that as the aids which the understanding derives from experience are seldom recorded in writing, or even described in words, every succeeding inquirer finds himself, at the commencement of his philosophical pursuits, obliged to struggle with the same disadvantages which had retarded the progress of his predecessors. If the more important practical rules, which habits of investigation suggest to individuals, were diligently preserved, each generation would be placed in circum

VOL. II.

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stances more favourable to invention than the preceding; and the progress of knowledge, instead of cramping original genius, would assist and direct its exertions. In the infancy of literature, indeed, its range may be more unbounded, and its accidental excursions may excite more astonishment than in a cultivated and enlightened age; but it is only in such an age that inventive genius can be trained by rules founded on the experience of our predecessors, in such a manner as to insure the gradual and regular improvement of science. So just is the remark of Lord Bacon: "Certo sciant homines, artes inveniendi solidas et veras adolescere et incrementa sumere cum ipsis inventis."

The analogy between the mechanical arts and the operations of scientific invention, might perhaps be carried further. In the former, we know how much the natural powers of man have been assisted by the use of tools and instruments. Is it not possible to devise, in like manner, certain aids to our intellectual faculties ?

That such a query is not altogether chimerical, appears from the wonderful effects of Algebra (which is precisely such an instrument of thought, as I have been now alluding to) in facilitating the inquiries of modern mathematicians. Whether it might not be possible to realize a project which Leibnitz has somewhere mentioned, of introducing a similar contrivance into other branches of knowledge, I shall not take upon me to determine; but that this idea has at least some plausibility, must, I think, be evident to those who have reflected on the nature of the general terms which abound more or less in every cultivated language; and which may be considered as one species of instrumental aid which art has discovered to our intellectual powers. From the observations which I am afterwards to make, it will appear, that, without general terms, all our reasonings must necessarily have been limited to particulars; and, consequently, it is owing to the use of these, that the philosopher is enabled to speculate concerning classes of objects, with the same facility with which the savage or the peasant speculates concerning the individuals of which they are composed.