Perhaps we may find a natural explanation of the true, and not very hidden sense of these signs, by comparing the fundamental doctrines in the elder Greek philosophy and science of nature. Thus, in the writings of Plato, mention is often made of the one and of the other, or of unity and duality, as the original elements of nature and first principles of all existence. By this is meant the doctrine of the first opposition and of the many oppositions derived from the first; and also of the possible, and conceivable, or required adjustment and compromise between the two, and of the restoration of the first unity and eternal equality anterior to all opposition, and which terminates and absorbs in itself all discord. Thus these eight koua, and mathematical signs or symbolical lines of ancient China, would comprise nothing more than a dry outline of all dynamical speculation and science. And it is therefore quite consistent that the old sacred book which contains these principles of Chinese science should be termed either the book of unity, or the book of changes; for doubtless this title refers to the doctrine of an absolute unity, as the fundamental principle of all things, and to the doctrine of differences, or oppositions or changes springing out of that first unity. This doctrine of an opposition in all things, in thought as in nature--will become more apparent if we reflect on the new and brilliant discoveries in natural philosophy. For as in this science, the oxygen and hydrogen parts in the chemistry of metals, or the positive and negative end of electrical phenomena, in the attracting and repelling pole of magnetism, reveal such an opposition and dynamic play of living powers in nature; so in this philosophy of China, the abstract doctrine of this opposition and dynamical change of existence seems to be laid down with a sort of mathematical generality, as the basis of all future science. In our higher natural philosophy, indeed, all this has been proved from facts and experience; and, besides, this dynamic life forms but the one element, and the one branch of the science to be acquired; and a philosophy founded entirely on this dynamical law of existence, without any regard to the other and higher principle of internal experience and moral life, intellectual intuition and divine revelation, would be at best a very partial system, and by no means of general application; or if a general application of such a system were made, it must lead to endless mistakes, errors and contradictions. That such a system of dynamical speculation and science, if extended to objects where it cannot be corroborated by facts--to all things divine and human, real, possible, or impossible, will undoubtedly lead to such a chaotic confusion of ideas; we have had a memorable experience in the German "Philosophy of Nature" of the last generation;[45] a philosophy which consisted in a fanciful play of thought with _Polarities, and