it is engraved on pages of adamant, and attested by the affirmation of the Godhead. It tells us, in words that cannot lie, that the soul is immortal from its birth; that the strong and inextinguishable desire we feel of future being is the true and natural impulse of a high-born and inextinguishable principle: and that the blow which prostrates the body and imprisons it in the grave, gives pinions to the soaring spirit, and crowns it with freedom and triumph. But this is not all it tells us, too, that gross matter itself is not necessarily corruptible: that the freedom and triumph of the soul shall hereafter be extended to the body; that this corruptible shall put on incorruption, this mortal immortality, and a glorious and beatified reunion succeed. By what means such reunion is to be accomplished, or why such separation should be necessary, we know not,-for we know not how the union was produced at first. They are mysteries that yet remain locked up in the bosom of the great Creator, and are as inscrutable to the sage as to the savage, to the philosopher as to the schoolboy;-they are left, and perhaps purposely, to make a mock at all human science; and, while they form the groundwork of man's future happiness, forcibly to point out to him that his proper path to it is through the gate of humility. LECTURE III. ON HUMAN UNDERSTANDING. HAVING taken a brief survey of the essence and duration of the soul, mind, or intelligent principle, as far as we have been able to collect any informa tion upon this abstruse subject, from reason, tradition, and revelation, let us now proceed, with equal modesty and caution, to an examination into its faculties, and the mode by which they develope themselves, and acquire knowledge. 66 66 "All our knowledge," observes Lord Bacon, "is derived from experience." It is a remark peculiarly characteristic of that comprehensive judgment with which this great philosopher at all times contemplated the field of nature, and which has been assumed as the common basis of every system that has since been fabricated upon the subject. Whence," inquires Mr. Locke, comes the mind by that vast store which the busy and boundless fancy of man has painted on it with an almost endless variety? Whence has it all the materials of reason and knowledge? I answer, in a word, from experience. In this all our knowledge is founded; from this the whole emanates and issues." M. Degerando, and, in short, all the French philosophers of the present day, in adopting Locke's system, have necessarily adopted this important maxim as the groundwork of their reasoning; and though, as a general principle, it has been lately called in question by a few of the ablest advocates for what they have ventured to denominate the Theory of Common Sense, and especially by Professor Stewart,* as I may perhaps find it necessary to notice more particularly hereafter, it is sufficient for the present to observe that the shrewd and learned projector of this theory, Dr. Reid, admits it in its utmost latitude: "Wise men," says he, "now agree or ought to agree in this, that there is but one way to the knowledge of nature's works, the way of observation and experiment. By our constitution we have a strong propensity to trace particular facts and observations to general rules, and to apply such general rules to account for other effects, or to direct us in the production of them. This procedure of the understanding is familiar to every human creature in the common affairs of life, and IT IS THE ONLY ONE BY WHICH ANY REAL DISCOVERY IN PHILOSOPHY CAN BE MADE." Now the only mode by which we can obtain experience is by the use and * Philos. Essays, vol i. p. 122. Inquiry into the Human Mind, p. §. exercise of the senses, which have been given to us for this purpose, and which, to speak figuratively, may be regarded as the fingers of the mind in feeling its way forward, and opening the shutters to the admission of that pure and invigorating light, which in consequence breaks in upon it. It must be obvious, however, to every one who has attended to the operations of his senses, that there never is, nor can be, any direct communication between the mind and the external objects the mind perceives, which are usually, indeed, at some distance from the sense that gives notice of them. Thus, in looking at a tree, it is the eye alone that really beholds the tree, while the mind only receives a notice of its presence, by some means or other, from the visual organ. So in touching this table, it is my hand alone that comes in contact with it, and communicates to my mind a knowledge of its hardness and other qualities. What, then, is the medium by which such communication is maintained, which induces the mind, seated as it is in some undeveloped part of the brain, to have a correspondent perception of the form, size, colour, smell, and even distance of objects with the senses which are seated on the surface of the body; and which, at the same time that it conveys this information, produces such an additional effect, that the mind is able at its option to revive the perception, or call up an exact notion or idea of these qualities at a distant period, or when the objects themselves are no longer present? Is there, or is there not, any resemblance between the external or sensible object and the internal or mental idea or notion? If there be a resemblance, in what does that resemblance consist? and how is it produced and supported? Does the external object throw off representative like. nesses of itself in films, or under any other modification, so fine as to be able, like the electric or magnetic aura, to pass without injury from the object to the sentient organ, and from the sentient organ to the sensory? Or has the mind itself a faculty of producing, like a looking-glass, accurate countersigns, intellectual pictures, or images, correspondent with the sensible images communicated from the external object to the sentient organ? If, on the contrary, there be no resemblance, are the mental perceptions mere notions or intellectual symbols excited in it by the action of the external sense; which, while they bear no similitude to the qualities of the object discerned, answer the purpose of those qualities, as letters answer the purpose of sounds? Or are we sure that there is any external world whatever? any thing beyond the intellectual principle that perceives, and the sensations and notions that are perceived; or even any thing beyond those sensations and notions, those impressions and ideas themselves? Several of these questions may perhaps appear in no small degree whimsical and brain-sick, and more worthy of St. Luke's than of a scientific institution. But all of them, and perhaps as many more of a temperament as wild as the wildest, have been asked, and insisted upon, and supported again and again in different ages and countries, by philosophers of the clearest intellects in other respects, and who had no idea of labouring under any such mental infirmity, nor ever dreamed of the necessity of being blistered and taking physic. There is scarcely, however, an hypothesis which has been started in modern times that cannot look for its prototype or suggestion among the ancients; and it will hence be found most advantageous, and may perhaps prove the shortest way to begin at the fountain-head, and to trace the different currents which have flowed from it. That fountain-head is Greece, or at least we may so regard it on the present occasion; and the plan which I shall request leave to pursue in the general inquiry before us will be, first of all, to take a rapid sketch of the most celebrated speculations upon this subject to which this well-spring of wisdom has given rise; next, to follow up the chief ramifications which have issued from them in later periods; and, lastly, to summon, as by a quo warranto, the more prominent of those of our own day to appear personally before the bar of this enlightened tribunal, for the pur * See the author's Study of Medicine, vol. iv. p. 46, edit. 2, 1825 pose of trying their comparative pretensions, and of submitting them to your impartial award. The principal systems that were started among the philosophers of Greece to explain the origin and value of human knowledge were those of Plato, of Aristotle, of Epicurus, and of the skeptics, especially Pyrrho and Arcesilas; and the principal systems to which they have given birth in later or modern times, are those of Des Cartes, Locke, Berkeley, Hume, Hartley, Kant, and the Scottish School of Common Sense, at the head of which we are to place Dr. Reid. I had occasion to observe, in our first series of lectures,* that it was a dogma common to many of the Greek schools, that matter, though essentially eter nal, is also, in its primal and simple state, essentially amorphous, or destitute of all form and quality whatever; and I farther remarked, that the groundwork of this dogma consisted in a belief that form and quality are the contrivance of an intelligent agent; while matter, though essentially eternal, is essentially unintelligent. Matter, therefore, it was contended, cannot possibly assume one mode of form rather than another mode; for if it were capable of assuming any kind, it must have been capable of assuming every kind. and of course of exhibiting intelligent effects without an intelligent cause. Form, then, according to the Platonic schools, in which this was principally taught, existing distinct from matter by the mere will of the Great First Cause, presented itself, from all eternity, to his wisdom or logos, in every possible variety; or, in other words, under an infinite multiplicity of incorporeal or intellectual patterns, exemplars, or archetypes, to which the founder of this school gave the name of ideas; a term that has descended without any mischief into the popular language of our own day; but which, in the hands of the schoolmen, and various other theorists, has not unfrequently been productive of egregious errors and abuses. By the union of these intellectual archetypes with the whole or with any portion of primary or incorporeal matter, matter immediately becomes imbodied, assumes palpable forms, correspondent with the archetypes united with it, and is rendered an object of perception to the external senses; the mind, or intelligent principle itself, however, which is an emanation from the Great Intelligent Cause, never perceiv ing any thing more than the intellectual or formative ideas of objects as they are presented to the senses, and reasoning concerning them by those ideas alone. It must be obvious, however, that the mind is possessed of many ideas which it could not derive from a material source. Such are all those that relate to abstract moral truths and pure mathematics. And to account for these, it was a doctrine of the Platonic philosophy, that, besides the sensible world, there is also an intelligible world; that the mind of man is equally connected with both, though the latter cannot possibly be discerned by corporeal organs; and that, as the mind perceives and reasons upon sensible objects by means of sensible archetypes or ideas, so it perceives and reasons upon intelligible objects by means of intelligible ideas." The only essential variation from this hypothesis which Aristotle appears to have introduced into his own, consists in his having clothed, if I may be allowed the expression, the naked ideas of Plato, with the actual qualities of the objects perceived; his doctrine being, that the sense, on perceiving or being excited by an external object, conveys to the mind a real resemblance of it; which, however, though possessing form, colour, and other qualities of matter, is not matter itself, but an unsubstantial image, like the picture in a mirror; as though the mind itself were a kind of mirror, and had a power of reflecting the image of whatever object is presented to the external senses. This unsubstantial image or picture, in order to distinguish it from the intellectual pattern or idea of Plato, he denominated a phantasm. And as he supported with Plato the existence of an intelligible as well as of a sensible world, it was another part of his hypothesis that, while things sensible are * Serres & Lecture L ceived by sensible phantasms, things intelligible are perceived by intelligiphantasms; and consequently that virtue and vice, truth and falsehood, , space, and numbers, have all their pictures and phantasms, as well as its, houses, and animals. picurus admitted a part of this hypothesis, and taught it contemporanely at Mitylene, but the greater part he openly opposed and ridiculed. He curred in the doctrine that the mind perceives sensible objects by means sensible images; but he contended that those images are as strictly mateas the objects from which they emanate; and that if we allow them to sess material qualities, we must necessarily allow them at the same time ossess the substance to which such qualities appertain. Epicurus, therebelieved the perceptions of the mind to be real and substantial effigies, to these effigies he gave the name of ciowa (idola), or SPECIES, in contrainction to the unsubstantial PHANTASMS of Aristotle, and the intellectual or ative IDEAS of Plato. He maintained that all external objects are perally throwing off fine alternate waves of different flavours, odours, cos, shapes, and other qualities; which, by striking against their appropriate ses, excite in the senses themselves a perception of the qualities and ence of the parent object; and are immediately conveyed by the sentient anel to the chamber of the mind, or sensory, without any injury to their ure in the same manner as heat, light, and magnetism pervade solid subices, and still retain their integrity. And he affirmed, farther, that instead he existence of an imaginary intelligible world, throwing off intelligible ges, it is from the sensible or material world alone that the mind, by the rcise of its proper faculties, in union with that of the corporeal senses, ves every branch of knowledge, physical, moral, or mathematical. f this view of the abstruse subject before us be correct, as I flatter myself s, I may recapitulate in few words, that the external perceptions of the id are, according to Plato, the primitive or intellectual patterns from which forins and other qualities of objects have been taken; according to Arise, unsubstantial pictures of them, as though reflected from a mirror; and, Fording to Epicurus, substantial or material effigies; such perceptions be under the first view of them denominated IDEAS; under the second, PHANMS; under the third, idola, or SPECIES. While such were the fixed and promulgated tenets of Plato, Aristotle, and icurus, there were other philosophers of Greece, or who at least have been denominated, that openly professed themselves to be without tenets of any d; who declared that nothing was known or could be known upon any ject; and who, consequently, inculcated a universal skepticism. Of this irious class of disputants, who were suffered to wander at large without a ait waistcoat, there are two that are pre-eminently entitled to our attenn, Pyrrho and Arcesilas. Pyrrho studied first in the atomic school of Deocritus, and seems to have lost his senses upon the question of the infinite visibility of matter, a question which has not unfrequently given birth to the me disease in modern times. He first doubted the solidity of its elemenry atoms,-he next found out, that if these be not solid, every thing slips vay from the fingers in a moment-the external world becomes a mere show and there is no truth or solidity in any thing. He was not abie to prove the lidity of the elementary atoms of matter. He hence doubted of every ing; advised all the world to do the same; and established a school for the urpose of inculcating this strange doctrine. In every other respect he was man of distinguished accomplishments, and so highly esteemed by his ountrymen, as to have been honoured with the dignity of chief priest, and xempted from public taxation. But to such a formidable extreme did this isease of skepticism carry him, that one or more of his friends, as we are ravely told in history, were obliged to accompany him wherever he went, hat he might not be run over by carriages, or fall down precipices. Yet he contrived, by some means or other, to live longer than most men of caution and common sense; for we find him at last dying of a natural death, at the good old age of ninety. Arcesilas was one of the successors to Plato in the academic chair, and founder of the school that has been known by the name of the MIDDLE ACADEMY. Plato, in his fondness for intellectual IDEAS, those creatures of his own imagination, had always given a much greater degree of credit to their testimony than to that of the objects which compose the material world; believing that the mind was less likely to be imposed upon than the external senses. And with so much zeal was this feeling or prejudice followed up by Arcesilas, that he soon began to doubt, and advised his scholars to doubt also, of the reality of every thing they saw about them; and at length terminated his doubts in questioning the competency of reason itself to decide upon any evidence the external senses might produce, though he admitted an external world of some kind or other. And upon being reminded, by one of his scholars, who had a wish to please him, that the only thing which Socrates declared he was certain of was his own ignorance, he immediately replied, that Socrates had no right to say even that-for that no man could be certain of any thing. It was against this unhappy madman, though, in other respects, like Pyrrho, excellent and accomplished scholar, that Lucretius directed those forcible verses in favour of the truth and testimony of the senses, as the only genuine means of acquiring knowledge, which have been so often referred to, and so warmly commended in the controversy of the present day : Who holds that naught is known, denies he knows Yet grant e'en this he knows; since naught exists Search, and this earliest notion thou wilt find E'en though the mind no real cause could urge * Denique, nihil sciri si quis putat, id quoque nescit The passage is too long for quotation, and the reader may easily turn to it at his leisure, |