We do not claim to have supplied the full solution of the problem concerning the dualism or materialism of the real with this discussion on the theme of Logic. This solution cannot (we repeat) be expected, save from all the philosophic sciences together, that is to say, from the complete system. But we can already see, from the logical point of view, that the dualists and materialists cannot avoid the task of showing that the nature or matter, which they elevate to a principle of the real or to one of the two principles of the real, is not: firstly, the mere negation of the spirit, nor secondly, a form of the spirit, nor thirdly, the abstraction of the natural sciences. They must also show that it answers to something conceivable and existing, outside or above the spirit. Logic can pass onward at this point, saying of materialists and dualists what Dante said of the devils and the damned struggling in the lake of burning pitch: "And we leave them thus encompassed." [Sidenote: _Nature as empirical distinction of an inferior in relation to a superior reality._] The word "nature" has yet a fourth meaning (but this time altogether empirical), which is clear in those propositions which distinguish natural life from social life, natural men _(Naturmenschen)_ or savages from civilized men, and again natural from human beings, animals from men, and so on. Nature, in this sense, is distinguished from civilization or humanity, and thus the sole reality is divided into two classes of beings: natural beings and human beings (which are sometimes also called spiritual as compared with the former, which are called material). The vague and empirical nature of this distinction is at once perceived from the impossibility that we meet with of assigning boundaries between civilization and the state of nature, between humanity and animality. Man can be only empirically distinguished from the animal, the animal from the vegetable, and vegetables from inorganic beings, which are organic in their own way. Certainly, what are called _things_ are not organic, for example a mountain or a plough-share; but they are not organic, because they are not real, but aggregates, that is to say, empirical concepts. In the same way, a forest is not organic, though it is composed of things vegetating, nor a crowd, though composed of men. When we treat of things in the above sense, we can say with some mathematicians that _things_ do not exist, but only their _relations._ Hence if the dualists feel able to affirm that the two classes of beings, natural and human, are based upon the existence of two different substances and upon the different proportions of these in each of the two classes, the task of proving the thinkability of the two substances and the different proportions of the compound falls upon them. [Sidenote: _The naturalistic method and the natural sciences as extended to superior not less than to inferior reality._]