and the design of the art of logic is to hold forth the manner of attaining that knowledge with most ease and expedition.

From these views of the nature and end of logic, it is apparent that it is one of the first arts to which we should apply our attention in our progress towards knowledge, as affording the best means of fortifying and improving our understanding. The more acute the understanding is, it will be more successful in the investigations of science. The less it is liable to err, the more certain and expeditious will be its progress. The more we are acquainted with those prejudices and partialities which have misled other reasoners, the less danger of mistake will there be. The better we understand the nature of the instrument we employ, the more expert and successful may we reasonably expect to be in the use of it. Every thing, then, in logic, that does not contribute to improve the understanding, and to promote our progress in useful knowledge, I shall not hesitate to pronounce unworthy of attention; but every thing, on the other hand, that promotes these ends, cannot obtain more attention than it deserves.

I am well aware that no art ever gave occasion to so much idle research, and fanciful refinement, as that of which I now speak. No art has so much bewildered and repressed every useful exertion of the understanding, as that which pretended to enlighten and improve this faculty, and to guide it in the road to truth. All the efforts of human genius, all the learning which for many centuries prevailed in Europe, were subtle disquisitions and puzzling distinctions about the method of investigating knowledge, without applying that method to any important inquiry. All the syllogism of the schools, after the thousands of volumes that have been written upon it, and after the employment of a

UTILITY OF LOGIC.

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series of ages to bring it to perfection, never enriched science or business with one useful discovery.

Let us not, however, rashly conclude, that these abuses furnish a proof of the general inutility or insignificance of the art to which I now call your attention. It is curious even to survey the ingenuity with which so many men have gone wrong, with the endless perplexities in which they have involved themselves. To point out these is one of the purposes of this work; but it is of more substantial utility to learn the nature of truth, and the operations of the human mind, which are concerned in the discovery and extension of knowledge.

As the sophistry, then, and absurdity, with which logic has been disgraced, are no valid objections against the use of it, so neither is the argument, that many men reason often very justly without any acquaintance with its rules. There is in all mankind some natural logic, for it is one of those arts which may be learned by practice, without the knowledge of theory. One of the best methods of making progress in the art of reasoning, is actual practice, or the acquisition of the habit of examining a train of ideas that constitute an argument; and of this branch of the art all men acquire some share by experience; many men acquire a great deal. But, though long experience in sound reasoning may render us expert logicians, in the same manner as practice, without the knowledge of principles, may form eminent practitioners in any other art; yet this success will not justify any inference against the utility, or even the propriety of theory. The end of all theory in the arts is to render us more methodical and reputable performers, and it can scarcely fail to produce this effect, when properly applied.

What is the theory of an art? It is a philosophical

delineation of the principles on which the art is founded, of the end it has in view, and of the means by which it proposes to accomplish that end. From this delineation are deduced the rules of the best practice, which are commonly illustrated from the experience of the most successful practitioners. A theory of an art, then, is a collection of all the knowledge which can be obtained concerning that art, from the combined information of all preceding theorists and practitioners. It points out the most patent and direct road to success, and it marks all the corners and obstructions, at which improper deviations are most likely to be committed; so that, after having learned the theory, nothing remains but to obtain the habit of ready and accurate practice, in order to render us able and successful performers.

Although, then, many men are good reasoners who never learned logic, yet the knowledge of that art may be neither superfluous nor nugatory; because an acquaintance with it may either facilitate our progress in becoming good reasoners, or may enable us to reach greater eminence in that line, than those who have not enjoyed the advantages we possess; and if we acquire by it either of these emoluments, it is of too much importance not to attract our serious attention.*

[* Logic has its use in improving the condition of men: it teaches, or may be made to teach, them to think. The active intellect has two parts, one of which originates our thoughts, and may be called the suggestive, whilst the other checks and judges thoughts as they arise, and may be called the critical power. Thoughts are continually suggested without the consent of the will. The suggestive power may be educated as certainly as, though more gradually than, the critical. The discovery which we call a flash of genius, a happy thought, really depends as much upon previous acquirements, as the power of stating a case or applying a rule does. All discipline of the suggestive must proceed from the critical power it is by a long, careful, patient analysis of the reasonings by which others have attained their results, that we learn to think more correctly ourselves. He who reads over a work on logic probably thinks no better when he rises

As the object of logic is to teach the best use of our rational faculty, both in investigating and in communicating truth, the theory of it, and the materials of which that theory consists, are deduced from this end. That theory, accordingly, consists of two parts; the nature of ideas, which are the materials on which we reason, and the nature of the faculties or operations of the mind which are concerned in reasoning. Before we can reason, we must have ideas; and before we can reason rightly, we must understand what kind of operation reasoning is. The explication of both comprehends the whole of logic which is of any use.

In explaining the nature of ideas, and of the operations employed about them, one of two methods must be adopted. We must either treat them separately, or in conjunction. We must either first discuss the ideas, and then the operations, or we must carry on the account of both at the same time. The latter is the better method, because one of the chief means of explaining the nature of ideas is, to point out the operations of which they are the objects; and one of the chief means of illustrating the operations is, to present the single ideas, or the clusters of ideas, about which the operations are exerted. This latter method we cannot hesitate to follow; and, in adopting it, all we have to do is, to specify and illustrate the operations from experience, and then to explain the single ideas, or the collections of ideas, about which each operation is conversant.

up than when he sat down; but if any of the principles there unfolded cleave to his memory, and he afterwards, perhaps unconsciously, shapes and corrects his thoughts by them, no doubt his whole powers of reasoning gradually receive benefit. In a word, every art, from reasoning down to riding and rowing, is learnt by assiduous practice, and if principles do sny good, it is proportioned to the readiness with which they can be converted into rules, and the patient constancy with which they are applied in all our attempts to excel.-Thomson.]

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CLASSIFICATION OF IDEAS.

The operations employed in the investigation of truth are commonly reckoned three-perception, judgment, and reasoning. By perception is understood that operation by which the mind sees and becomes acquainted with every single idea it possesses. By judgment is understood that operation by which the mind discovers the agreement or the disagreement of any two ideas it may have occasion to compare, in order to discover truth and knowledge. By reasoning is understood that operation in which the mind compares two ideas by means of one or more intermediate ideas, in order to discover the amount of what is commonly called a demonstration or an argument. This short account of these operations must at present suffice; for, as they comprehend the whole theory of logic, I am afterwards to resume and consider them separately.*

Ideas are arranged into classes, and different names assigned, according as they are simple or complex, distinct or confused, adequate or inadequate, particular or abstract.

A simple idea, as its name insinuates, can be contemplated only in one view. It cannot be divided or taken to pieces, because it does not consist of parts, being naturally indivisible.

Most of our ideas of the qualities of bodies are of this class-as hard, soft, round, smooth, white, black, cold, hot; all ideas, per haps, of tastes, smells, sounds—as bitter, sweet, low, loud; and many of our ideas of the feelings and operations of the mind-as of desire, aversion, hunger, pain, thinking, willing, discerning, reasoning.

[* Mr. Thomson distributes the subject into three parts, the first treating of conception, or the power of forming general notions; the second of judgment, or the power of deciding whether two notions agree or not; and the third of syllogism, or the power of drawing one judgment from another. To these a fourth part, in which method, or the power of using the other three functions in the discovery of truth, is explained, has been usually added, which answers to applied logic.]