readers. This, however, is no valid objection to the subject itself, and should only stimulate our endeavors both to understand it ourselves and to render it plain to others.

But even after the writer has done the best he can to be understood, his object may be defeated by the reader. He who would read a book on this subject as he would a novel, has mistaken his business. He must address himself to it as a labor, not as a pastime. He must pause, and converse much with his own experience and reflections; he must compare with them what he reads. The rapid and superficial manner in which most reading is now done, peculiarly unfits the mind for the investigation of grave subjects.

The remark often quoted from Cicero, that the human mind is like the eye, which sees every thing but itself, relates to the difficulty of demonstrating facts not cognizable by the senses. When the chemist analyzes a glass of water, our eyes tell us, at once, into what parts he resolves it. But when the philosopher analyzes the human mind, we must refer to our personal experience for the facts in question, and are liable to mistake his meaning. Hence this is a peculiarly difficult subject upon which to write intelligibly. On none ought the reader to exercise more caution, reflection, patience.

To the objection, that philosophy sometimes contradicts common sense, assuming that it is wiser to trust the latter than the former, I reply, if by common sense be meant the mere vulgar apprehension, irrespective of inquiry and reflection, sound philosophy must needs sometimes contradict it. The great principles of truth lie below the surface. The celestial orbs roll in their paths, not as the vulgar mind apprehends, but as searching

science demonstrates. In most of the natural sciences, principles are reached only by a process of experiment and induction beyond the reach of many minds.

But if by common sense be meant the sober sentiment of mankind in general, relating to subjects which they examine and understand, the above objection has weight. Every person is constantly making experiments upon his own mind, and may thus learn its powers and propensities. He needs books, not so much to teach him the mental faculties as to inform him how to designate and classify them, how to improve them, and to what ends to apply them. Hence common sense has here an important service. Her sober decisions are of the highest authority, and no philosophy can permanently, stand against them.

The philosophy of the human mind is not truly taught by bewildering abstractions and scholastic refinements, much less by bold hypotheses and doubtful speculations, but by a simple and plain exposition of the mental facts, leaving the reader, for the proof of them, to his own experience and reflection. As all minds are cast in the same mould of humanity, he who thus studies his own mind becomes acquainted with those of the whole human race. He is a mental philosopher.

The alleged want of a perceived connection between mental philosophy and the practical interests of life is more relevant to writers of continental Europe than to those of Great Britain and America. The former are the more contemplative, the latter the more practical. It is desirable to combine the two. The deep, rich undercurrent of thought and emotion, which habits of profound contemplation tend to produce, gives great

strength and beauty to the mental character. Indeed, it is only the contemplative man that is in the true sense a philosopher. Still it must be acknowledged that even the English and Scotch authors, notwithstanding their strong utilitarian tendencies, have failed to make sufficiently prominent the practical bearings of this subject. It sustains a most important relation to our highest interests as social, moral, and religious beings, which no effort should be wanting to render obvious.

The study of man as a physical being has perhaps, also, in this connection, received too little attention. The metaphysical has been kept too widely apart from the physical. They unite in the same being; the spiritual beginning where the physical ends, and carrying out the same wise design. We trace the operations of matter so far as we can; all beyond we refer to spirit. The facts of the physical philosophy of man thus underlie those of mental philosophy, and their relation to it should be carefully examined. Yet I am far from believing that a sound and entire system of mental science can ever be erected upon a mere physical basis. It has been said, with perhaps too much assurance, that "if we are to have a correct philosophy of the human mind, it must come from physicians." The true philosopher of the mental must study also the physical in man; but if he study only the latter, I am afraid that it will cost him more than one lifetime to educe from nerves, brains, fibres, tissues, ganglia, and vital fluids, a perfect system of mental philosophy.

Let anatomy carry its dissecting process to the extreme limit of possibilities, minutely tracing the nervous fibrile of each muscle to its termination in the cerebral mass; let surgery thrust its

glittering blade into the living flesh, and search, amid palpitating muscles and throbbing nerves, for the pathological phenomena in their most hidden retreats; let physiology appropriate each demonstrated fibre for its sensitive and motor functions; let it diligently pursue the wonderful movements of life, as it outspeeds the lightning in its courses around and through the human frame, until it escapes and is there no more; let it place itself as near as possible to the mechanism of thought, and claim to possess the narrow isthmus which unites the luminous and mental way; let phrenology next come forth to fix the seat of consciousness in the sensorium, explain how impulses are communicated to the mind from without, and sent forth from the mind by the motor nerves to the muscles, through the nervogalvanic circuits of the brain; let it even definitely indicate the organ of every mental faculty, and take its precise gauge and dimensions; finally, let etheropathy come to the service; let it hypothesize the existence of an all-pervading ethereum, by which bodies and minds act upon each other; let it show how the human mind, like the magnet, may, by this ethereum, pierce through solid masses, may send forth its impulse, and even its vision, to distant beings and things; let it thus reveal, if possible, the mysteries of a supposed clairvoyance,—all these may serve to throw light upon mental philosophy. Still, we ere long reach the inevitable point, where neither one nor all of them avail where we must take naked facts as they rise up, unexplained, from the spirit world.

Those who make no account of physical inquiries on the one hand, and those who admit nothing but what they explain on the other, are alike in fault. Let them proceed together. What neither can do alone, they may unitedly accomplish. Let them

bring their respective offerings to the same altar. All their demonstrations may yet be seen to harmonize and to confirm each other. Such an event would be a beautiful triumph of That investigations of a subject so profound, commenced at opposite points, and pursued by ways so different, should finally reach the same conclusions, would not be unlike those sublime triumphs in astronomy won by the united demonstrations of the calculus and of the telescope.

I have endeavored to make the work strictly progressive, like a mathematical treatise, commencing with the origin of intellect, and conducting it through its several stages of growth up to its highest earthly development. The interest and profit with which subjects like this are studied eminently depend on such an arrangement. The human mind loves order; it looks for a beginning, a progress, and an end; every step in the course being necessary to a clear understanding of what follows.

The first part is devoted to psycho-physiology, or the mutual relations of life, mind, and matter. The design is to explore the physiological sources of the mental phenomena, to show wherein the intellectual is dependent on the physical, and the physical on the intellectual, to examine the evidence for the mind's immortality, and to point out the origin of its knowledge. The way is thus prepared for our strictly psychological inquiries.

We proceed, in the second part, to examine the nature and sources of our primary knowledge. The distinction usually made by the terms original and acquired is here indicated by the terms primary and secondary. The reason is, that I