origin of sensation and consciousness; for in his work on "The Old Faith and the New," he did not enter into that question at all. On the other hand, he makes in his last-mentioned work a remarkable confession. In answering the question—how do we determine our rule of life?—he comes to speak of the position of man in nature, traces a law of progress in nature, and says: "In this cumulative progression of life, man is also comprised, and, moreover, in such wise that the organic plasticity of our planet (provisionally, say some naturalists, but that we may fairly leave an open question) culminates in him. As nature can not go higher, she would go inwards. 'To be reflected within itself,' was a very good expression of Hegel's. Nature felt herself already in the animal, but she wished to know herself also." But still stronger is the following expression: "In man, nature endeavored not merely to exalt, but to transcend herself." In [§ 1, Chap. II], we shall have to speak of this important acknowledgment of teleology in nature, which such an antagonist of teleology as Strauss makes in the above-quoted remarks about a progress in nature and a will of nature; but here we are more interested in the equally remarkable acknowledgment of the fact that man can not be explained from nature alone—that he is something which transcends nature. For that (according to Strauss) nature, in originating man, not only intended to transcend herself, but really did transcend herself and, that she succeeded in her intention, we can infer from the moral precept which Strauss gives: "Do not forget for a moment, that thou art human; not merely a natural production."
The result of our investigation, therefore, is that
with self-consciousness and free moral self-determination something specifically new came into existence which had its antecedent condition in a previous state of existence, but has not yet found its sufficient explanation in this antecedent state.
§ 2. The Origin of Sensation and of Consciousness.
The limits of our knowledge show themselves still more clearly in the attempts to explain the origin of consciousness and its lowest form—sensation. Self-consciousness is without doubt ideally nearer to consciousness in this, that both are an immaterial activity; and yet we found no demonstrable bridge which leads from consciousness to self-consciousness. Still broader is the gulf between the material and the immaterial, between the unconscious and the conscious,—or, to describe the two realms with names which bring them nearest together, between that which is without sensation and that which has sensation: a gulf to bridge which philosophy also has vainly exerted its utmost efforts, as has been well known since the "supernatural assistance" of Descartes and the "preëstablished harmony" of Leibnitz. Wherein lies the real necessity that there should be sensation? How does the material become something that is felt? What is the demonstrable cause (not the condition, but the cause) of a sentient subject? To these questions, every science up to the present day lacks an answer. As is well known, DuBois-Reymond, in his previously-mentioned lecture upon "The Limits of our Knowledge of Nature," declares the origin of sensation and of consciousness to be one of two limits, beyond
which we have not only to say "ignoramus," but "ignorabimus."
In abstracto, we might think of two attempts at bridging over this gulf: the first one is that we try to transform sensation itself into something material, and the other is that we attribute sensation also to that which, according to our observation, seems to be without sensation; namely, to matter and its elements, the atoms. Both of these attempts have been made—the former by D. F. Strauss in his "The Old Faith and the New," and by the English philosopher, Herbert Spencer, in his "First Principles of Philosophy;" the latter, first pointed out by Schopenhauer, was taken up and farther developed by Zöllner in his work, "Ueber die Natur der Kometen" ("Nature of the Comets"), Leipzig, Engelmann, 1872, and with special acuteness by an "Anonymus" in the work: "Das Unbewusste von Standpunkt der Physiologie und Descendenztheorie" ("The Unconscious from the Standpoint of Physiology and Descent Theory"), Berlin, Duncker, 1872.
Strauss says, in the previously-mentioned work: "If, under certain conditions, motion is transformed into heat, why may it not, under other conditions, be transformed into sensation?" And Herbert Spencer says, in his "First Principles of Philosophy," (page 217): "Various classes of facts thus unite to prove that the law of metamorphosis, which holds among the physical forces, holds equally between them and the mental forces. Those modes of the unknowable which we call motion, heat, light, chemical affinity, etc., are alike transformable into each other, and into those modes of the unknowable which we distinguish as sensation,
emotion, thought: these, in their turns, being directly or indirectly retransformable into the original shapes."
But motion—even the finest material motion, that of ether, (which, in consequence of the very important discovery of the conservation of force and of the mechanical equivalent of heat, made by Robert von Mayer, at present is taken to be heat)—is so decidedly a material process, the sensation of motion is so decidedly a reflex of the material in something immaterial, that the assertion of a transformation of motion into sensation seems to us only to change the point of view, and not to explain the difference, but to efface it. And we think that the appeal of Strauss from his contemporaries, who do not understand him, to posterity, who would understand him better and esteem him, has but little prospect of being operative.