The Rev. Dr. Porter, of Yale College, has published an important work upon that branch of psychology which relates to the faculties of cognition. Whatever be the judgment pronounced upon this treatise, no man can withhold his respect for the self-denying labor, both in the way of study and of composition, which has been devoted to its production. The size of the book is something stupendous. It is a large octavo of nearly seven hundred pages (printed, we regret to say, upon that harsh, cottony paper in which New York publishers seem to delight), in three sizes of print, of which the largest would not be unusual for a duodecimo while the smallest is painful to read. The work is designed primarily for a text-book, and the part in the largest type "is somewhat technically phrased and formally propounded in order that it may be learned more readily for the examinations of the class-room." But as the philosophical world was also to be addressed and the discussion must accordingly be carried in many places beyond the depth of learners, and inasmuch also as the author wisely thought it well to put more information into the hands of his scholars than they were to be positively required to master, the book has been more than doubled by the addition of matter in two sizes of small print, that in the middle-sized type being suitable for general students, and that in the smallest consisting chiefly of historical and critical notices.

General readers in metaphysics will hardly find the book to their taste. The appearance of it is not inviting; the type is too small, the volume too large, and the paper disagreeable. A style studiously technical and formal, even if it were not stiff and awkward and of a magisterial tone, would not attract them. Nor is a compendium of 699 numbered sections, with scarcely any unity of conception developing through them all, precisely what such readers desire. But it is admirably fitted for a college text-book. The formal and bald manner in which the arguments on either side are laid down is eminently adapted to nourish the logical power of the student. Great pains have been taken to give a full and rigidly precise account of the meaning of the principal terms employed, thus inculcating one of the most essential requisites for accurate thinking upon abstract subjects. The author's talent for explaining words is well illustrated in the chapter upon consciousness. He shows somewhat more favor to modern German terminology than we should approve. For example, "sense-perception," instead of external perception, seems to us to have little to recommend it. The scholastic terminology forms a system at once precise and elastic. New terms can be constructed in accordance with the principles of it which may be understood by any one who is acquainted with these principles. This system, together with the accretions which it received in the seventeenth century, has the character of a somewhat obsolete but yet universal language; it is not confined to the philosophers of any particular nation, but is equally the possession of all. It is the basis of the actual English terminology, and has even passed in great degree into ordinary English speech. The modern German terminology, on the other hand, is unsettled and unsystematic; most of its single words correspond precisely to no single English words, and its method of compounding them is foreign to our conceptions of grammar. For these reasons, we think that the basis of English terminology should be allowed to remain as it actually is, scholastic; and certainly no one who favors a movement in the direction of Aristotelianism, as Dr. Porter partly does, should oppose this position. But once admit that such should be the basis of our terminology, and no doubt we should adhere to it consistently, except in cases in which it altogether fails us. In the present case it has not failed us. The phrase "external perception" would be quite intelligible to any educated person, even if it were a newly invented term. But in point of fact it is quite familiar both in English and in German. If it be objected that some persons believe in an external perception not through the senses, still Dr. Porter is not one of these; but even if it were judged proper to take account of that mystical and fictitious faculty, the term "external sensuous perception" might be adopted. Dr. Porter's using "representation" for imagination and memory appears to be another case of borrowing from the German. Representation is wanted in a general unpsychological sense, and as a psychological term it has already been used in two other senses besides that in which Dr. Porter takes it. Either "the representative faculty" or the "imagination" might have been employed advantageously in the last sense, as they were, in fact, by Hamilton. In using words cognate with "activity" we are inclined to suspect that Dr. Porter has been somewhat influenced by German usage, although we do not find that he anywhere defines any of these words, the ambiguity of which has often led writers into fallacies.

Another character of the work which makes it suitable for purposes of instruction is the impartiality with which the whole ground is gone over, no one or more faculties or phenomena being dwelt upon at such inordinate length as to encroach upon the space due to the others. The student will consequently receive the best armor against plausible theories which answer well for the facts that concern one mental process, but which may conflict with those that concern another. Another merit is that in the smaller type the student will generally find some notice of doctrines not contained in the text he is required to learn, and some references to the books in which those doctrines are maintained. Accordingly, when he has once become thoroughly familiar with this treatise by a year's study of it, it will always serve him as an invaluable index of reference in any further psychological studies which he may choose to pursue. We must not omit to say that the doctrines which it teaches are entirely conformable to orthodox theology, and quite free from any materialistic leanings. A young mind thoroughly imbued with Dr. Porter's teachings will be likely to get its philosophy so bound up with its religion that it cannot part with either unless it parts with the other.

The historical notices are full and valuable. They do not cover every important question, and in some places, as where psychology trends upon logic, are comparatively meagre; but some account is given of most of the more prominent discussions. These notices, considered as criticisms, will be thought by some to carry but little weight and to present no very noticeable characteristics. Considered as statements of fact, they are learned. The accounts of ancient opinions have evidently not been written without a study of the latest commentaries. In what relates to the history of the Scotch and English schools, even professed students of philosophy will find much that is fresh and instructive. The great defect of this part of the book is that, as a general rule, no account whatever is given of recent works, these being cited only by title. This omission detracts very seriously in some cases from the value of the book. Twenty-five pages of the finest print are devoted to an account of the various theories of perception without the least mention, except by title, of the writings of Fechner, Wundt, Trendelenburg, George, Lotze, and others, whose investigations may truly be said to be of more value than all the others put together.

Mediæval doctrines, which are seldom intelligibly treated, are not treated intelligibly here. The reader is for the most part expected to gather the opinions of the masters and doctors from single quoted sentences, which are often utterly meaningless or even misleading to those who have not given special attention to scholastic philosophy. Take for example the account of nominalism and realism on pages 405-407. What is a person not already acquainted with the subject to make of the statement that a certain master taught that a universal is "indifferenter" in all the singulars under it? How correct a notion is he likely to form of Abelard's doctrine from being told that he "sermones intuetur et ad illos detorquet quicquid alicubi de universalibus meminit scriptum"? Will he understand, as he should, that the sermo means a word actually in application by the mind as a predicate? Considering the historical importance of Roscellin, and considering the fact that, though an extreme nominalist, his doctrines were associated with those of Scotus Erigena, who was a sort of Platonistic idealist, is it quite sufficiently explaining his views to quote that sentence of Anselm's in which he is said to have thought that universal substances are the breath of the voice, that the wisdom of man is the soul, and that color is the colored body? It would have been easy to explain, first, that the vox was regarded by grammarians of that age as something incorporeal, because it is produced by the percussion of the palate and the air, but is not either, and because a natural motion cannot produce a new body, and also because the vox is in several ears at once, whereas a body can only be in one place at one time; that we have positive reason to think that Roscellin believed this; that, in the second place, reasoning (as we may suppose) like others in that age from such facts as that the same line which, when measured by one measure (a foot) is equal to two, when measured by another (an inch) is equal to twenty-four, and that the wall of a house is on the one hand a whole in itself and on the other a part of a house, he came to believe (as we are positively informed) that all mathematical relations--that is, all relations of parts and whole--exist not in the body itself, but only in the incorporeal words which may be applied to it; and that, thirdly, he thence inferred that those universal essences of things, genera and species, since they essentially have parts and are parts, themselves are not things, but incorporeal voces. Of any interruption in the course of the controversy between the twelfth and thirteenth centuries our author tells us nothing, although the discovery of all the works of Aristotle except the two short treatises already known, and of the writings of the Arabian commentators, had in the interval between Abelard and Albertus so changed the whole face of scholasticism that it is rarely indeed that any writer of the twelfth century except Peter Lombard and Gilbertus Porretanus is quoted at all in the thirteenth. The facts that Albertus had properly no opinion of his own and that that of St. Thomas was very vacillating (as was notorious in the fourteenth century) are not mentioned. Scotus's realism is said to be identical with that of these writers except as to the hæcceity; but the difference is more important. The Thomistic view was that of the two elements of the individual thing--that is to say, the matter and the form, or that which makes it to be, and that which makes it, if it is to be, to be as as it is--the form is always universal, the matter, or at least signate matter (this or that matter), is always singular. Their union is an individual, but it is a union in which the form is as such actually universal in itself. Scotus admitted that in the singular thing there is nothing actually universal; all generality results from a relation of reason. Nevertheless, when a general predicate is attached by the mind to a thing, the proposition so formed may be true, and since the same predicate may also be truly asserted of other things, it is true that there is something in the thing which, though actually contracted to the grade of singularity, is in its own nature not repugnant to being predicated of many. There is, then, a distinction between a predicate predicated of many and the singular forms in the several things by virtue of which the same general predicate is true. Yet since this general predicate is true, it really is in the several things, although it is there in the grade of singularity and identified with these singular forms. Thus there is a really, but only potentially, general form in the singular thing which yet in that thing in itself does not differ from the singular thing. This is the famous doctrine of formal distinctions, which is the central idea of the whole Scotistic philosophy. This formed also the very point of Occam's attack, for his whole notion of a reality was that of a thing which is in itself whatever it really is. This he was able to see must be something devoid of all quality and all relations. All qualities and relations, according to him, are terms, subjects and predicates of written, spoken, or thought propositions; and the qualities and relations of things can consist in nothing except that the mind naturally applies to them such and such terms. Prof. Porter says the controversy came to a close early in the fourteenth century, but Occam did not die until 1347, and it certainly raged with the greatest fury after his death.

The Scotch school of philosophy, to which this work belongs, is too old a tree to bear good fruit. Its method consists in an appeal to consciousness--that is to say, to what all men know and know that they know (p. 113)--supported by some familiar facts and occasional anecdotes. Such a procedure is not wholly useless. The common sense of mankind has so little impulse to seek explanations of facts that it is hardly tempted to twist them, and he who busies himself with reproducing ordinary beliefs is free from so deep an absorption in laborious experiments and observations as to overlook what lies upon the surface. The great mistake of writers of this sort has been that they have had an ambition to be more than accurate describers of common beliefs and unanalyzed facts. That natural self-consciousness, when heightened by direct effort, becomes a scientific knowledge of the soul, is not the doctrine of modern psychology. This opinion is disappearing, and with it will probably disappear some of that morbid tendency to introspection, the prevalence of which justified the advice given by the editor of a magazine to a contributor, "Should you ever be drowned or hung, be sure and make a note of your sensations; they will be worth to you ten guineas a sheet." The efforts which Dr. Porter recommends, "to hope and fear again and again, simply that we may know more exactly how it seems or what it is to perform [sic] or experience these states," to say nothing of their double futility (for we cannot so hope and fear, and if we could it would teach us little of the essence of these emotions), are very unwholesome.

Within the Scottish school we should suppose that this book must take a very high rank. Indeed, as long as Mr. Mansel (even if he properly belongs to that school) produces nothing more, we do not see what living writer, unless it be Dr. McCosh, is to dispute with Dr. Porter the honor of the very first place. In the character of his genius and learning more like Dugald Stewart than any of the other coryphæi of that philosophy, Dr. Porter's relation to Scotch psychology is somewhat similar to that of Hamilton, inasmuch as he modifies the pure Scotch opinions by an admixture of the prevalent German views. As Hamilton treated high metaphysics upon modified Kantian principles, so Porter imports into the same branch of philosophy considerations which have been derived in large measure from the study of Trendelenburg. His metaphysic starts, as it ought, with a theory of inductive reasoning. He holds that the reason why an innumerable number of instances will not justify the inference that all swans are white, while a single instance would suffice to show that all men's heads are placed upon their shoulders, is because a failure of the latter induction, unlike a failure of the former, would be "entirely incompatible with the ideal of beauty and convenience to which we assume that nature would certainly conform." Since then the validity of induction rests upon certain assumptions of this sort, these assumptions are not themselves demonstrable either by induction or otherwise, but are original and self-evident truths. These intuitions are as follows: 1st, that an object is either substance or attribute; 2d, that objects originate by a causative energy; 3d, that objects are in space and time; 4th, that properties and laws which are known indicate and signify other properties and laws; 5th, that nature adapts objects and powers to certain ends; and 6th, that the rational methods of the divine and human minds are similar. These ultimate facts and relations are not learned by the ordinary processes of thought, imagination, and perception. They are "not apprehended by, but involved in, these processes," and must, therefore, be referred to a separate faculty. They are first apprehended in a concrete, not in an abstract, form. We do not set out with the universal belief that every event has a cause, but as we apprehend each separate object by perception or consciousness we apprehend it as caused. Such apprehension is a proposition, and from such propositions are derived the various concepts, substance and attribute, cause and effect, means and end, etc. These concepts being apprehended abstractly and compared with the processes of cognition are found to be essentially involved in them all. Finally, it is perceived that over against all objects of experience, as having these various relations of dependence, there must be some independent correlates upon which they depend. Thus all things being extended, there must be a space; in correlation with all things as being caused there must be a First Cause, etc. The whole argument upon this subject, which occupies some two hundred pages, is followed out with great ability. It will be perceived that this theory of intuition has a general resemblance to that of Dr. McCosh.

It is easy to see upon what side such a theory may expect attack. Its essence is that the process by which we attain our first knowledge of these fundamental ideas is essentially different from the other processes of the mind. Now, if it were shown that all the other mental processes, whether of cognition, emotion, or action, were essentially one, it would be hard to prevent men from believing that this process alone did not conform to their common formula. Accordingly, it is not surprising that we find throughout Dr. Porter's work a tendency to exaggerate the distinctions between the faculties and to overrate the importance of these distinctions, and to explain facts by the general supposition of a peculiar faculty even when such a supposition requires it to be as complex as the facts themselves, in order to explain them in detail. But though the reader of this book would scarcely suspect it, there is a movement which is steadily coming to a head towards identifying all the faculties. It is the motive of all sensualism, it is the latest mood of psycho-physical inquirers, and it is beginning to be consciously felt even in this country. If that doctrine should once be established, it would not avail Dr. Porter's theory that he had correctly answered the question why the inference that all men carry their heads upon their shoulders is so strong, because it would appear that the principle of design which effects this inference is only a derivative one, and that the only assumption which can enter into every induction is no assumption about the things reasoned upon at all. Dr. Porter's opinion is, that the assumptions involved in induction are the only basis of religion; but the only assumption which can be essentially involved in scientific inference is the assumption of the validity of scientific inference. But to make the validity of scientific inference the only possible basis of religion approaches very near to pure rationalism--a doctrine that is not in the interest of religion, because it subordinates religion to science. We are inclined to suspect that the metaphysician, whether spiritualist or materialist, is in this dilemma; either he must look upon his problems with the cold eye of science, and have no other feeling for the eternal interests of man than the curiosity with which he would examine a trilobite; and then, being in a state of mind essentially irreligious, he can arrive at no result that would really help religion, for at most he can only say to mortal man that it is most likely that there is a God, which is no assurance; or he must bring the feelings of a religious man into the inquiry, and then he is as incompetent to treat the problem as a physician is to judge of his own case. Can it possibly be, that the directest and most uncritical faith in the object which commands one's adoration--the faith of a little child--is the only actual motive to religion which there ever has been or ever will be, and that all reasonings pro or con upon the fundamental proposition of religion must be entirely irrelevant and unsatisfactory?