to obedience and unity under legitimate authority, lest they be utterly destroyed. For the earth, "let" it "be filled with the knowledge of the Lord, as the waters fill the great deep." Then shall "the nations learn war no more."

"Then shall PEACE wreathe her chain

Round us forever."

Happy day! Jesus, master, onward speed its coming glory!

ART. II.-GERMAN MATERIALISM-THE NATURALISTIC SCHOOL.

[FROM THE FRENCH OF THE REVUE DES DEUX MONDES-PART SECOND.]

III.

EVERY philosophic mind, in reading the above exposition of the system of Dr. Büchner, has doubtless noticed a strange gap: the author, who explains everything by matter, has entirely forgotten to tell us what matter is, and what he understands by the word. That, however, is not a question of slight importance, and it has for centuries busied men who were neither fools nor children. Is it not known that into the idea of what we call matter and body two very different elements enter: one which comes from our sensations, and is nothing but the totality of the diverse modifications of our organs; the other comes from without, and is really distinct and independent of our impressions? Now when it is said that matter is the original of things, this is evidently spoken of matter as it is in itself, and not as it appears to us; for if an analysis should prove that matter is composed only of our sensations, and includes nothing external, matter itself would thereby disappear, being but a modification of our minds, and materialism would change into idealism. It is therefore fully evident that the first obligation of a materialistic system is to distinguish what comes from ourselves from what comes from without in the notion of body or matter; but this distinction is difficult, as the history of science shows. Mr. Büchner has wholly neglected it; his system is defective, therefore, in its basis.

Let us try to do what he has not done; let us show by analy

sis how obscure and imperfect is the notion of matter; how far from self-sufficient it is; how it vanishes and disperses on examination. "It is an intangible something," says Fenelon, "which melts in my hands when I press it."

We must first ask what a body is, vulgarly understood. A body is a solid, colored, resisting, extended, mobile, odorous, warm or cold mass. In a word, it is an object which strikes my senses, and I am so habituated to living among such objects, to using, enjoying, hoping for, and fearing them, that they seem to me the most real things in the world. I laugh at those who bring them in question, and, if I wish to imagine my own mind, I give it the form of a body. What is there solid and faithful in this kind of representation of matter? Philosophy to answer this question begins by distinguishing the apparent from the real. This distinction the most positive and exact sciences have made familiar to us. In astronomy everything depends upon the distinction of real from apparent movements. If we consult appearances the sun seems to move from east to west, drawing with him the planets. In reality the earth moves and has two motions, of which we feel neither; the one a rotation on its axis, the other a revolution about the sun. We must likewise distinguish in the stars apparent from real size, apparent from real position. To get the true height of a star in space, astronomers are obliged to allow for the deviation of luminous rays through the atmosphere, that is, for refraction. Optics in general teach us not to confound visible appearances with the true form, true size, true position, true movement of objects.

We are authorized by all these facts, and by many others well known, to ask ourselves whether, in the notion that we form of bodies, there is not a part, which must be attributed to the observer himself, which comes from and disappears with him. Among the qualities that we attribute to matter there are two especially which appear to us to animate nature, and wanting which she would seem to us delivered to death: light and sound. Well, let us ask physicists what is sound and what is light. Here is their response: Sound and light are vibrations, that is, movements. Let us pause a moment upon fine theory of physics, which has shed so much light upon the question of external perception.

this

If we strike a cord drawn taut, we impart to it a vibratory go-and-come movement, which our senses can seize; the touch feels it shiver under the thumb; the sight, in place of a very distinct line, perceives a cord swollen toward the middle and much less luminous, whose swelling goes on decreasing till it returns to a state of rest. This kind of movement is what we call a vibration, and it is from this simple elementary fact that the whole vibratory theory has sprung, so important in modern physics, and whose vocation is to so grand a future. Now, while the vibration lasts, while the finger feels the cord shiver, we hear a sound. The sound begins and ends with the vibration. Furthermore, the most exact experiments and the most precise calculations establish a rigorous relation between the pitch of the sounds produced and the number of vibrations, a number which is in constant relation with the length, tension, etc., of the cords. It is, therefore, proper to affirm, that the sole cause of the sound, or sonorous sensation, is a movement. This movement is communicated by the air, which is itself a vibratory body, to the ear, a mechanical instrument arranged to collect and transmit aerial vibrations to the acoustic nerve. It is there, there only, that the mechanical sound. ceases and is replaced by a sensational sound. There motion is transformed into sensation, an unexplained and perhaps absolutely inexplicable phenomenon.

What is certain is, that until the moment when the acoustic nerve comes into play, there is absolutely nothing without ourselves but a vibratory motion, such that if we suppose for a moment the auditor to disappear, the nerve capable of perceiving sound paralyzed or destroyed, no animal on the earth or in space able to hear, then there will be absolutely nothing without us which resembles, in any respect whatever, what we call a sound.

Much time, many experiments, and many reasonings were required to apply to light this theory of vibrations. Sonorous vibrations may be perceived by the senses, luminous vibrations cannot; the elastic medium which transmits sounds may be perceived by the senses, it is the air; the elastic medium which is thought to transmit light is apparent to no sense, it is the ether. It follows that, as to sound, the vibratory theory is a result of experiment, it is merely a summary of the facts; as

to light, on the contrary, the vibratory theory is a hypothesis conceived by the mind, which may be more or less verified by experiment: thence the tardiness with which the theory was introduced and the difficulties it has encountered. However, to-day, it is definitively allowed by physicists, and here also they have been bold to say: Considered apart from ourselves, apart from the sensitive subject, apart from the seeing eye, light is only motion. The luminous sensation is a phenomenon proper to the living eye, which can take place only in and by it.

But here is something much more extraordinary, which proves in a decisive manner to what a degree our sensations are subjective and dependent upon our organs, and how greatly our ideas of matter as the senses present it to us should be rectified by the mind, namely, the identity nearly admitted to-day by all physicists between light and heat. What is more different, from the sensation point of view, than these two orders of phenomena? They seem even very often separate. I can be warm in darkness, for instance in mines, and cold amid flashing light. Despite these superficial and apparent contradictions, the experiments of Melloni have so multiplied the analogies between the two agents that science hardly hesitates in affirming their identity. Heat, like light, moves in straight lines and with the same speed; it is reflected like light; like light it is refracted and by the same laws; it is transmitted through bodies, like light itself; finally, it is known that by combining two lights we may produce darkness. Well, by combining two sources of heat we may produce cold: this a remarkable experiment of Mr. Foucault's has proved. To conclude with a remarkable and recent treatise of physics: "Never, when we address ourselves to a simple ray, do we find a variation of light without a corresponding variation of heat. Such an agreement in results gives ground for the belief that heat and light are perchance only different manifestations of one and the same radiation; the difference would result only from the kind of modification which the object struck may undergo. Upon the sight, this radiation would give the impression of light; upon the touch, the impression would be wholly different."

Outside ourselves, outside the sensitive subject, there are not

these two things, light and heat, but only one, which is diversified in our organs of sensation. Heat is light perceived by the tactile nerves, and light is heat perceived by the optic nerve. Finally, as we have seen that light is merely a motion, so heat is a mere motion. Thus, to sum up the whole theory, the sensitive or living subject, in a word, the animal, being abstracted, there is in nature neither heat nor cold, light nor darkness, noise nor silence; there are only varied motions, whose laws and conditions are determined by mechanics.

Physiology comes to the support of physics in demonstrating the subjectivity of our sensations. This is the fundamental law of our sensations according to Müller, the great German physiologist: "The same cause may produce different sensations in different species of nerves; the most different causes may produce the same sensation in every category of nerves. Thus electricity brought into contact with each of our senses produces in each of them special sensations: in the eye luminous phenomena, in the ear sounds, in the mouth savors, in the tactile nerves pricklings. Narcotics likewise produce internal phenomena of hearing and vision, buzzing in the ears, scintil lation in the eyes, stinging in the nerves of touch. Reciprocally the luminous sensation is produced in the eye by etherial vibrations, by mechanical action, by a shock, a blow, electricity, and by chemical operations. It is the same with the other senses. Müller concludes from these facts that the senses have each their distinct, determinate energies, which are, as it were, vital qualities, and he approves that beautiful theory of Aristotle, an anticipation of all that we have just said, to wit, that "Sensation is the common act of the object and subject of sensation."

I am far from affirming that there is nothing external and, as it is called, objective in our perceptions, and that everything is reducible to diverse states of the sensitive subject. Nothing is further from my belief than such a supposition. Excellent reasons may doubtless be given to establish the reality of the outward world, and the best is that we cannot help admitting it. There is then no room for doubting the reality of external things, and such a doubt will ever be frivolous; but what is not frivolous is the difficulty we experience in determining