soning power. And on the other hand, a great quickness and clearness in the perceptions of relations is necessarily attended, (other things being equal,) with an augmented efficiency of reasoning.

§. 9. Of habits of reasoning.

But whatever may be the mental traits, that render, in particular cases, the reasoning power more or less efficient, its efficacy will undoubtedly depend, in a great degree, on Habit. The effect of frequent practice, resulting in what is termed a HABIT, is often witnessed in those, who follow any mechanic calling, where we find that what was once done with difficulty comes in time to be done with great ease and readiness. The muscles of such persons seem to move with a kind of instinctive facility and accuracy in the performance of those works, to which they have been for a long time addicted.

There is a similar effect of frequent practice in the increase of quickness and facility in our mental operations; and certainly as much so in those, which are implied in reasoning as in any others. If, for instance, a person has never been in the habit of going through geometrical demonstrations, he finds his mind very slowly and with difficulty advancing from one step to another; while on the other hand, a person, who has so often practised this species of argumentation, as to have formed a habit, advances forward from one part of the train of reasoning to another with great rapidity and delight. And the result is the same in any process of moral reasoning. In the prosecution of any argument of a moral nature, there is necessarily a mental perception of the congruity of its several parts, or of the agreement of the succeeding proposition with that, which went before. The degree of readiness in bringing together propositions, and in putting forth such perceptions, will greatly depend on the degree of practice.

§. 10. Of limitations of the power of reasoning.

We shall prosecute these general views of the subject of reasoning with the further remark, which has perhaps already suggested itself, that this faculty is essentially and permanently circumscribed and limited in certain respects. From the statements, which have been made, it appears, that the great law of association is directly and very effectively concerned in every process of this kind. It is to this law we are indebted for the introduction of propositions, having a bearing upon the subject of inquiry and debate, and suitable to the occasion. We are no more able by a mere act of volition to secure the existence of applicable and conclusive points in any given argument, than by mere volition to give creation to our thoughts in the first instance.

Persons, therefore, of the most gifted intellect are held in check, and are restrained by the ultimate principles of their mental constitution. These are boundaries, which they cannot pass ; and men, who are capable of the greatest efforts in framing arguments, will be no less sensible of this truth, when they carefully examine the course of their thoughts, than others.

§. 11. Of reasoning in connection with language or expression.

There is often a want of correspondence between the purely mental process in reasoning and the outward verbal expression of it. When persons are called upon to state their arguments suddenly and in public debate, they often commit errours, which are at variance with the prevalent opinion of their good sense and mental ability. This is particularly true of men, who are chiefly engaged in the ordinary business of life, or are in any situation where there is a constant call for action. The conclusions, at which such persons arrive, may be supposed to be generally correct, but they frequently find themselves unable to state clearly and correctly to others the process of reasoning, by which they arrived at them. Oliver Cromwell, the famous English Protector, is said to have been a person, to whom this statement would well apply. The complicated incidents of his life, and the perplexities of his situation, and his great success sufficiently evince, that he possessed a clear insight into events, and was in no respects deficient in understanding; but when he attempted to express his opinions in the presence of others, and to explain himself on questions of policy, he was confused and obscure. His mind readily insinuated itself into the intricacies of a subject, and while he could assert with confidence, that he had arrived at a satisfactory conclusion, he could not so readily describe either the direction he had taken, or the involutions of the journey. - "All accounts, says Mr. Hume, agree in ascribing to Cromwell a tiresome, dark, unintelligible elocution, even when he had no intention to disguise his meaning; yet no man's actions were ever, in such a variety of difficult cases, more decisive and judicious."

Such instances are not unfrequent. Mr. Stewart somewhere mentions the case of an English officer, a friend of Lord Mansfield, who had been appointed to the government of Jamaica. The officer expressed some doubts of his competency to preside in the court of chancery. Mansfield assured him, that he would not find the difficulty so great, as he imagined.--"Trust, said he, to your own good sense in forming your opinions, but beware of stating the grounds of your judgments. The judgments will probably be right; the arguments will infallibly be wrong."*

The perplexity, which is so often experienced by men

• Many of the most respectable and valuable men in our legislative assemblies are persons, who are rarely heard in debate. While they are known to possess reach of thought and correctness of judgment, they exhibit in public discussion little more than confusion and apparent inability. Mr. Jefferson, author of the Declaration of American Independence, is declared by one of his illustrious associates, who knew him well, to have been a silent member of the Continental Congress. And yet he had at that period the reputation of literature and science, and of being a happy writer; and lent great aid by his promptness and decision on committees. A remark of a similar purport is made by Mr. Jefferson in his recently published Memoirs, in respect to Washington and Franklin. (See North American Review, Vol. XXII, p. 386.)

engaged in active life, in giving a prompt and correct verbal expression to the internal trains of thought, is probably owing in part to a want of practice of that kind, and in part to certain mental habits, which they have been led, from their situation, to form and strengthen. In a thousand emergencies they have been obliged to act with quickness, and at the same time with caution; in other words, to examine subjects, and to do it with expedition. In this way they have acquired exceeding readiness in all their mental acts. The consequence of this is, that the numerous minute circumstances, involved more or less in all subjects of difficult inquiry, are passed in review with such rapidity, and are made in so very small a degree the objects of separate attention, that they vanish, and are forgotten. Hence these persons, although the conclusion to which they have come be satisfactory, are unable to state to others all the subordinate steps in the argument. Every thing has once been distinctly and fairly before their own minds, although with that great rapidity, which is always implied in a HABIT; but their argument, as stated in words, owing to their inability to arrest and embody all the evanescent processes of thought, appears to others defective and confused.

CHAPTER EIGHTH.

DEMONSTRATIVE REASONING.

§. 12. Of the subjects of demonstrative reasoning.

In the remarks, which have hitherto been made, the subject of reasoning has been taken up in the most general point of view. The considerations, that have been proposed, are applicable, in the main, to reasoning in all its forms. But it is necessary, in order to possess a more full and satisfactory conception of this subject, to examine it under the two prominent heads of Moral and Demonstrative.

There are various particulars, in which moral and demonstrative reasoning differ from each other; and the consideration of which will suggest more fully their distinctive nature. Among other things, DEMONSTRATIVE reasoning differs from any other species of reasoning in the subjects, about which it is employed. The subjects are abstract ideas, and the necessary relations among them. Those ideas or thoughts are called abstract, which are representative of such qualities and properties in objects as can be distinctly examined by the mind separate from other qualities and properties, with which they are commonly united. And there may be reckoned, as coming within this class of subjects, the properties of numbers and of geometrical figures; also extension, duration, weight, velocity, forces,