THE following treatises were originally destined to appear singly in the monthly parts of Liebig's " Annalen der Chemie," and should, from the time they were given in, have been commenced in July 1844. Accidental circumstances delayed their publication, and thus it happened that several of them became united in entire parts of that work, and then were first given to the public in March and May 1845. This will explain their somewhat unusual form.

In the present Second Edition there are some corrections, but, as a whole, the principal contents have remained unaltered ; my researches, continued without interruption during the several years that have elapsed,. have strengthened and confirmed the earlier observations. I have considered that I could not abandon the half-historical, half-systematic course of the enumeration of my observations, and the detail of my judgments upon them, since it is that of natural science generally, in which the correction of earlier experiments always keeps pace with the extension of our knowledge.

It was to be expected that a subject of so unusual and peculiar a kind as the present researches would meet with objections ; and I was aware beforehand that I should have to defend my experiments, and the deductions I had drawn from them, against ill-founded and groundless opposition.

The new field of research which was laid open pushes its lines too near the bastions of established formulae, frequently involves, in too many convolutions, all that exists in the present doctrines of natural dynamics, for the necessary space to be freely allowed to it. Yet I thought only of reasonable criticism of my observations, perhaps of unsuccessful repetitions of my experiments, arising here and there from faulty arrangement ; that my conclusions might be contested, or other views built upon the facts brought forward : but I was not prepared for an attack, which every true friend of science will unite with me in calling unprovoked, such as was made upon my work, and upon myself personally, by a Dr. Dubois-Reymond, in Karsten's " Fortschritte der Physik sm Jahre 1845." 'This naturalist does not find it at all neeessary to go into my experiments, and the conclusions deduced from them, but briefly and superficially designates my book as an " absurd romance," the details of which " it would be fruitless and to him impossible to enter." I believe both of these assertions. Fruitless ; because he has not understood them, and an uncomprehended and incomprehensible criticism is fruitless. Impossible ; because he has not read them in connection ; and to enter into a matter of which one has acquired no knowledge, is impossible. And that he really has not read them, but turned over the leaves in the fashion of a superficial and unscrupulous reviewer, is proved by his calling my work " the New Testament of Mesmerism :" thus he has not seen that it is the very first, in this field, which runs counter to Mesmer's views in most points, and places the phenomena on wholly different ground. With silly jests he says, he " is greeted by the magnetic tub and complex magic wares of the Baron von Reichenbach," &c. : thus he has not read that it is myself who makes an end of that tub and Mesmer's magnetic wares, in tearing down the veil from the mysteries, tracing them back to their bare physical contents, and replacing all previous phantasmagoria by sober investigation of nature. But as long as science exists, ignorance will have the most dogmatic judgment. This polished Berlinese then further pleases to throw commonplaces in my face, such as,—my treatise is one of the " most melancholy aberrations which have for a long time settled on a human brain ;" they are " fables," which deserve " to be thrown behind the fire ;" and more of the like learned vulgarity. Whoever assumes publicly to sit in judgment and pronounce sentence on a scientific work, is subject, first of all, to the duty of making himself thoroughly acquainted with its contents ; he has, moreover, like every other judge, to support the decision with the motives upon which he believes he is justified in grounding the same. This duty is the more irremissible in him, that his judgment is but one-sided, and requires the control of public opinion, while the attacked party may, if necessary, take arms against it. But a slanderous criticism, which is not ashamed to strip itself of all these conditions, is nothing else, in one word, than literary insolence, and of such measure, that is perhaps unexampled in ancient or modern literature : for it certainly has never and nowhere occurred that a reporter has had the boldness, or rather the silliness, to pass over a scientific production peremptorily, and with unprovoked insults, without any account, or any statement of his reasons,—without a single syllable of analysis of its contents. I have said silliness, because it is silly to throw stones which one can see will rebound on one's own head. Either my statements contained truths, which have existence and consistence in the physical world,—consequently must sooner or later be recognized, and put the ignorant reviewer to shame ; or they are based upon great errors, and in that case it must be an easy thing for him, in accordance with his duty, to disclose and elucidate them, and thereby to put away from himself the accusation of unfair trifling with the fame of his fellow-citizens : only, narrow-mindedness and silliness expose themselves thoughtlessly to both these dangers at once.

M. Dubois further says, he cannot enter into the details of my treatise, " because it would be altogether impossible for him to avoid unparliamentary language in so doing." The insolence he had poured out upon me was not unparliamentary, not rude enough ; he had store of still coarser quality. He has given a specimen of the delicacy of his manners, which restrains him from the use of it. I will relieve him from the necessity of any hypocrisy, and tell the truth : he had not the courage to venture on a discussion of the details of my treatises. The matter does not lie upon the surface ; the facts collected cannot be briefly set down by a fluent tongue ; and the conclusions drawn consequently from them cannot be washed away with watery ink. A fundamental investigation, however, requires pains, and costs labour ; this is inconvenient, perhaps fruitless, and perchance leads to scruples. And since, without such trouble, the matter cannot be thoroughly gone into, except at the risk of unripe judgments, the details are warily avoided, lest the critic should get rapped on the knuckles, or should subsequently be made to feel the scourge of the author. It is much easier and cheaper to skip away over the outside of a subject with a worthless superficiality, and by casting slurs upon it, to degrade it in public opinion, and then to shuffle out of it, in a cowardly way. M. Dubois need not lay the slightest compulsion upon himself to enter into the details of my treatise : I call him out into the arena, with his " unparliamentary language" of the Spree, and give him my word that he shall meet me, and I will give him just such an answer as he deserves.

The very nature of an experimental work renders it subject to defects ; it is just because we feel these defects in our knowledge, that we institute experiments, to perfect it, through the discovery of new facts. While we are engaged in these, we again become aware of ten, nay a hundred, new deficiencies ; the reader, too, on his part, probably desires another dozen, which have escaped the author ; and the reviewer perhaps still more. It is quite right, then, that they should be publicly indicated and be brought into discussion, so that the matters may be further worked out in new directions, or that what has already been obtained be safely placed beyond all doubt. This benefits every one, including the first discoverer of each new scientific fact.

My works will be as little free from defects as those of much more exalted men than I ever could be, least of all in the natural sciences. No one can have felt this more strongly than myself. Every criticism expressed in a good spirit I shall receive with thanks, and try to improve my work accordingly. But imperious abuse, from one who is profoundly ignorant of the work he reviews, must be repelled, and the reviewer must be taught to know the limits of decency. It is the interest, not only of myself, but of all who work and write, that weeds of this kind should not be left to flourish, but be raked out and cleared away.

That much more exalted men than myself do really fall into the greatest mistakes in their scientific works, I will not be content merely to have said, in my own defence, but I will at once prove it. M. Johannes Midler, our great physiologist, and the pride of Germany,whose excellent works are the oracle of his contemporaries,in his Handbook of Human Physiology (4th edition, i. 26), where he mentions the " so-called animal magnetism, the passes, imposition of hands, transfer of the so-called magnetic fluid," says, word for word : " Their stories are, however, a lamentable maze of lies, deceit, and superstition ; and it has only proved how incapable most physicians are of empirical investigation, and how little conception they have of a mode of examination which has become the universal method in the other natural sciences." But how, if it now turn out that it is, on the contrary, M. Muller himself who is and moves in that lamentable maze? How, if in my treatises exactly that mode of proof be applied which is carried out in the now universal method of the other natural sciences ? And how, finally, if exactly these tests have demonstrated and established by evidence, through hundreds of facts, the actual existence of such a fluid or dynamic, that produces surprising physical and physiological effects, by passes, imposition of hands, and transference, as distinctly as any other physical or physiological truth can be established in the same way ? Then, one would and must say, that the great Willer had considerably erred in a matter on which, without a previous examination, he had allowed himself to pronounce an injurious and hasty judgment, and that in a new edition of his Handbook he will expand those parts so hurried over. It will be noted as a striking instance of how the most distinguished men may fall into the greatest errors through prejudice or preoccupation ; may be subject to mistakes of such magnitude, that exactly that which they bitterly and unsparingly attribute to other people, finds its most accurate application in their very selves, and falls back upon their own heads.

M. Dubois, meanwhile, is under the scientific influence of M. J. Muller, as he tells us himself in the 58th volume of "Poggendorff's Annalen,"—is indeed his pupil,—and thinks that in proper respect to his exalted master he must swear " in verba magistri," for it is evident that his attack, where he honours me with " the most melancholy aberration of a human brain," agrees almost verbatim with M. Muller's " lamentable maze," (both appear to have a store of compassion for lamentably erring authors) ; and where the latter speaks of lies and deceit, the former thinks to hurt me with obscure and suspicious hints, as,—of concealed " peculiar and hidden ground of my treatise." . . . But these gentlemen " cannot see the forests for the trees" this time. An unconnected mass of the strangest phenomena, in nervous patients, is reported to them ; there is no rubric for such facts in the " system ;" and while the spectators were regarding theastonished faces and the embarrassment of the doctors, a Berlin grisette has made one of the learned gentlemen the sport of her wantonness. When he at last saw, in the mirror, that his ears were growing too long, he cried "Treason !" and all the thousand truths that now came crowding to the door for examination and recognition, were pitilessly hurled, unheard, from top to bottom of the stairs, as " lying, deceit, and superstition." This is, indeed, a convenient way of getting over the trouble of a fundamental investigation, but it is at the same time as one-sided and hasty, as unscientific and unconscientious.

Natural science, and all its branches, have originally run through a period of obscurity and error : physics were preceded by magic ; chemistry, by alchemy ; medicine, by the philosopher's stone ; astronomy, by astrology, &c. ; philosophy, theology, and jurisprudence, have passed through their phases of extravagance. Our first conceptions are always unclear, confused ; hence adapted to the wonderful, the mysterious, and so on to superstition and misuse. But it does not follow from this, that the enigmatic shell conceals no solid kernel. It is quite in character with the matter, and anything but unexpected, that the subject of sensitiveness, and the peculiar force on which it depends, should have to go through such a period of infancy in our notions ; and the more so in proportion as it shows itself, on the one hand, the less capable of limitation, and on the other, to have a deeper hold on the hidden sphere of the nerves. That these days of rudeness should have endured for seventy years, is really rather long in these enlightened times, but in great part owing to the almost criminal narrow-minded opposition of the gentlemen of the " exact sciences," who have turned to it, not only deaf ears, but even a kind of foolish hostility. Berzelius, who, as is known, accepted my researches with ardour, has assured me that for forty years he has always nourished the desire that some one would undertake this matter—which could not be groundless, —who would make it the subject of a special and fundamental examination, according to the present methods of investigation in the natural sciences ; and he rejoiced at last to have found, in me, one who would make a rational inquiry into it. The reason why this has been so long delayed, why the groping round about has come to no end, lies moreover in the fact that people so often begin to build the pyramid at the point ; they would wish to do first what they should do last—undertake to cure diseases ! Before striving for the slightest knowledge of the inner nature of the hidden force, they made a trade of the matter ! Then somnambulists and clairvoyants were met with, everywhere manifestations of force at its maximum, and in complication with inexplicable exalted conditions of disease. While struck with the phenomena on a large scale, and feeling unable to find an explanation of them, people neglected to inquire after the small beginnings, on which alone the basis of a scientific structure could be raised. Not from the lightning and the thunder have we gathered the theories of electricity and of sound ; not from the eruption of volcanoes have we drawn our knowledge of the expansive force of steam ; but just as our forefathers fabled about these natural phenomena, because they did not understand them, even so have the modern savons of the category to which M. Dubois belongs, talked nonsense about the so-called animal magnetism, because they did not know it. I will not speak of medical men, but it is no better with the physicists and physiologists ; the majority of the former have rejected all cognizance of it, because they cannot understand the connection of cause and effect ; and of the latter because they will not. However, this is not the path of the investigation of nature, and the offence against enlightenment is really greater in the latter than the former. It does not redound to the honour of our contemporaries to stand obstinately firm in that primitive condition of blind ignorance, and to refuse to see at all how monstrously they lay themselves open on this side.

Yet I have not found the difficulty of penetrating to the truth of these matters nearly so insurmountable as it is generally, timidly, asserted to be. All that gossip about lies and deceit is in reality quite misplaced ; when we examine more closely, it lies essentially not in the sensitive, but, on the contrary, in the subjectiveness of the pre-occupied, or not unfrequently incompetent inquirer. One must understand how to investigate, one must know how to question nature, if one would obtain a clear and instructive answer ; but it is not every one who can do this, so far as we know. I must say it, to the credit of the mixed population of Vienna, that among some hundreds of persons whom I have, up to this time, received more or less deeply into the sphere of my researches, and sixty of whom are publicly named in my writings, that there was scarcely a single one who gave me more than one or two exaggerated answers, and this rather from misapprehension than from dishonest intention, but which were immediately discovered and reformed by me. From the intimate, natural, and regular connection in which all these phenomena stand with each other, the threads of which I now hold surely in my hand, it is impossible for any one to continue to answer me falsely, even for a few minutes, without my at once detecting it. None of these people think of lying and deceiving ; they simply express what they see and feel, when I react upon them ; most of them evince a sincere and encouraging desire to make as clear as possible, to me, what they perceive and detect, in which zeal I find some compensation for the modifications from parties who ought rather to feel that they have reason to be thankful for my endeavours. All these almost countless answers to my questions agree in every case so perfectly, that all reasonable doubt must disappear before the evidence of the truth ; and in this beautiful agreement lies the warrant of their thorough credibility. When, however, the inquirer does not know how to put the questions, from want of skill how to manipulate with the apparatus, from ignorance of the conditions how to arrange the experiments, from want of tact to comprehend the answers, and from want of acuteness of understanding how to discover the relations of the observations to each other : then confusion and perplexity begin, misinterpreted results contradict each other ; and rather than look in the face his own weakness, and confess it to himself and others, he, a thousand times sooner, takes the dishonest subterfuge of accusing the observed person-of deceit. But the betrayer of nature and science is no other than the man who, from incapacity, has the rashness and foolishness to desire to stamp the truth with the mark of a lie.

Castle Reisenberg, near Vienna,
February 1848.

This work was already completed and printed in the spring of last year, but the occurrence of the German revolution threw obstacles in the way of its publication. These are now removed, and communication is re-established. It was necessary to make this note, in order to enable the reader to understand some dates which occur in the book, and which could not he reprinted.