This demonstration of truth is the proper act of the faculty› of reason. It is by reasonings and chains of arguments, depending one upon another, and originally founded on firstand self-evident principles, that the philosopher demonstrates the truth of his doctrines and propositions, in metaphysics, ethics, and geometry.

By extrinsic evidence, the certain knowledge that a thing exists, or is really what it is affirmed to be, is derived from the authority of testimony.

By the testimony of our senses, under due conditions, we obtain a true and certain knowledge of the existence of corporeal objects, and of external facts. The testimony of the senses is admitted, in courts of law, as evidence of facts.

By the testimony of men, under due conditions, we obtain a true and certain knowledge of the existence of distant objects, which we have never perceived by our senses;-by this means the certain knowledge of the existence of Rome or Constantinople is conveyed to those, who have never seen these places ;-or of the past existence of historical facts, such as of the battles of Pharsalia, and of Hastings, or of such persons as Julius Cæsar, and William the Conqueror. It is on the testimony of men that the certitude of all historical truth is founded. Indeed, when any public fact is attested by numbers, who, being themselves eye-witnesses of it, and having the testimony of their own senses concerning its existence, could not have been deceived; and who, though in many ⚫ cases divided in matters of opinion, in interests, in inclinations and customs, still all unite in attesting, in a uniform manner, the existence of the fact in question, could not be suspected of any design of deceiving others: in such circumstances, no reasonable man could admit a doubt of the truth of the testimony.

If the testimony of men furnishes evidence of the certitude of truth, how much more the testimony of God, who knows all things, as they are in themselves, and who cannot deceive us by any false testimony?

It may be observed, that the medium is not always the same, by which we obtain the certitude of truth, or the certain knowledge, that things really are what they are affirmed to be. We see the truth of self-evident principles, by intuitive evidence; we obtain the certain knowledge of metaphysical

and mathematical conclusions, by metaphysical and mathematical demonstrations; of the existence of corporeal objects around us, by the testimony of our senses; of the existence of distant objects or past events, by the testimony of men. And even in perceiving the existence of corporeal objects around us, different objects are perceived by different senses. Thus colour is perceived by the eye; sound, by the ear; taste and smell, by their respective senses. The secret opinions or intentions of a man cannot be known to his fellow-men, but by the means of some exterior sign or expression. The certain knowledge of what is commanded or forbidden by a legislator, can only be derived from the authoritative manifestation or promulgation of his law.

Nothing can be more unreasonable, than to seek the certain knowledge of truths and facts, by means, which are not naturally and specifically adapted to the object of inquiry; or to deny the truth of any doctrine, or the existence of any fact, because it cannot be demonstrated, or established by arguments, or testimonies, which have no analogy or connexion with them. Would it be reasonable, to deny the metaphysical doctrines of the spirituality or immortality of the soul, because they cannot be proved by the testimony of the senses? or to deny that the battle of Hastings was ever fought, or that there ever existed such a person, as William the Conqueror, because these historical facts cannot be demonstrated, like a mathematical problem, by lines and angles? or to deny the existence of colour, because it cannot be perceived by the ear; or of sound, because it cannot be perceived by the eye? To attempt to prove such objects by such means,. would be to pervert the order of nature, and to subvert the grounds of certitude.

CHAPTER II.

THE COMPETENCY OF HUMAN REASON AS A SURE GUIDE TO TRUTH IN MORAL AND NATURAL SCIENCES, Considered. -Its Deficiency, in many instances, regarding Natural Religion and Morality-and the physical Order of the Universe.

- BEFORE We come to the question, whether the certain knowledge of the truth of the revealed doctrines of Christianity can be obtained by the mere natural powers of human reason, or whether the truth of these doctrines can be proved by arguments drawn from the principles of natural science, it may in fairness be inquired, how far unassisted human reason, in its present state, is a sure guide to truth, even in matters that seem to be placed within the sphere of its natural capacity.

If we consider the history of contradictory human opinions, relative to almost every object of moral and philosophical science, we must conclude, that mere human reason, even as it existed in the most cultivated minds of ancient Greece and Rome, when left to itself, is incompetent to bring man to the certitude of moral and and natural truth, in a great variety of instances.

What contradictory doctrines have not been maintained, even by the most enlightened philosophers, concerning the nature and providence of God; the origin of evil; the spirituality and immortality of the soul; free-will; certain moral duties; the end for which man was created, and the means of obtaining happiness! On these subjects, we find great inconsistency or uncertainty, even amongst those, whose intellectual powers seem to have been the most perfect; such as a Socrates, a Plato, a Cicero, &c. Socrates complained of the obscurity of human reason. Plato, in his feeling of its insufficiency, prayed that some more enlightened guide might be sent from heaven, to lead man to truth and happiness.

Cicero was in painful doubt concerning various important points of natural religion. If mere human reason, in its present state, were the proper and sure means, by which man is to attain to the certitude of truth, in regard to those religious and moral questions which seem to belong to the class of natural sciences; surely those distinguished individuals, who possessed human reason in its greatest perfection, and who sought for truth with all the powers of their minds, would have formed a true and certain judgment on those important subjects of inquiry. But if each one had discovered truth, their opinions and doctrines would have been uniformly the same.

It is not only on these religious and moral subjects, which seem to belong to the class of natural sciences, that human reason feels the want of intrinsic evidence, to enable it to form a true judgment of things as they really are in themselves; but it finds itself frequently in the dark, when it wishes to discover truth in matters relating to the physical order of the universe. What a number of contradictory doctrines do we not see in the history of philosophical systems, concerning matter and motion, and the various operations of nature, which are daily exhibited before our eyes! Every object of our senses, from the sun to a grain of sand, from an elephant to the smallest insect, is a mystery to human reason. But the greatest of mysteries to man, in this sublunary world, is man himself, his body, and soul; their union, and co-operation; the action of the pure powers of his soul, and the connexion between volition and the motions of animal life. All these are mysteries, incomprehensible to human reason. And on these natural subjects, what contradictory doctrines have not been maintained by the most enlightened philosophers, even since the dark ages have passed away! Did not even Descartes and Locke, Leibnitz and Newton, maintain opposite systems? Each thought that he had intrinsic evidence or demonstration of the truth of his own; but on those points, on which they were in contradiction to one another, the light of human reason must have led either the one or the other of them into error.

If, in the moral and physical order of things, there are so many objects, the truth of which cannot be intuitively seen, nor be intrinsically demonstrated from principles of

natural science, so as to make it absolutely certain that the thing really is what we judge it to be; if nature, on every side, presents incomprehensible mysteries to the mind of man; can human reason expect to obtain intrinsic evidence of the truth of the supernatural objects of divine revelation? Can the private judgment of every individual, formed by a series of arguments from principles of natural science, be reasonably considered as the proper and sure means by which he is to obtain the certain knowledge of the truth of the revealed doctrines of Christianity? Is it reasonable to deny the truth of these doctrines, because it cannot be demonstrated by natural reason? May there not be some other medium, by which the certitude of the truth of the doctrines of divine revelation may be obtained, in a manner more congenial to the object of inquiry?