[28] There are several passages in the _Tao-tê ching_ where Nature could not be used to translate _Tao_; but this may in some cases arise from the fact that Lao-tzŭ’s conception of Nature was very different from ours. CHAPTER V. SPECULATIVE PHYSICS. What was Lao-tzŭ’s conception of the Cosmos? To this question we are unfortunately unable to give a clear and satisfactory answer. It is only occasionally, and then usually by way of illustration, that he alludes to the material world or to the physical and mental constitution of man. All that we can do, accordingly, is to examine the miscellaneous passages in which he refers to these subjects, and collect from them what information we can as to the notions which Lao-tzŭ entertained about the origin and nature of the universe; and we must be prepared to find under the head of speculative physics many more matters than ought properly, according to our ideas, to be so included. The first point to be noticed is that, as has been already seen, Lao-tzŭ refers all existing creatures to an eternal, all-producing, all-sustaining unity, which he calls Nature (Tao). He does not distinguish between mind and matter, nor would he, in my opinion, have recognised any fundamental or generic difference between them. Whether, however, spirit and matter were identical or diametrically opposite, they had a common origin in Tao. But though usually he thus refers all things to nature (Tao) as their first cause, yet he sometimes seems to speak of the universe as coming from nothing.[1] Nor is there any contradiction here, since Lao-tzŭ regarded non-existence (Wu 無) as in circumstances identical with existence (Yu 有); the latter being merely the former contemplated from a different point of view. This opinion, if not explicitly stated by himself, is at least implied in his writings, and is explicitly stated by one of his disciples.[2] It must be mentioned, however, that Chu-hsi (朱熹) ascribes the very opposite doctrine to Lao-tzŭ, who, he says, regarded existence and non-existence as _two_, whereas Chou-tzŭ (周子) regarded them as one.[3] In the Tao-tê Ching the originator of the universe is referred to under the names Non-Existence, Existence, Nature (Tao) and various other designations—all which, however, represent one idea in various manifestations. It is in all cases Nature (Tao) which is meant, and we are now prepared to examine the part which Lao-tzŭ assigns to this Tao in the production and regulation of the physical world.