We will not enter into a question here mooted by the author, leading to what Leibnitz calls the labyrinth of the continued (_Labyrinthus continui_), or of invisibles; we will content ourselves with pointing out that the reason here given is not by any means in conformity with the ideas of Kant--indeed, that it contradicts them. In fact, our author here applies to the two forms of sensibility the objection that Kant raised only about real things and the sensible world. The world, indeed, being composed of parts, can only be conceived as infinite by adding these parts to each other, and by thus supposing the actual reality of an infinite number. But it is not so with space, which, not being composed of parts, is consequently not representable by numbers. "There is only one single space, there is only one single time," says Kant. The notion of space is therefore not formed by the infinite addition of small portions of space and time. These are unities, not numbers. Hence illimitableness is given with the very intuition. "Space," says Kant, "is represented as a given infinite magnitude," _als eine gegebene unendliche Quantität_. Now, so soon as the infinite is _given_, instead of _being made_ by a mental addition, it seems to us that the above difficulty vanishes. Let us pass to the notion of substance and to that of cause. These two notions are necessary to render possible the connection of phenomena in the human mind. Our perceptions are, in fact, diverse; if they were only diverse, and had no unity, there would be no passage from one phenomenon to another; consciousness would arise and disappear with each phenomenon, to arise and die anew with the next, and so on. But then there would be no thought, for in order that thought should exist there must be at least two different things presented to the unity of consciousness. In other terms, we should be incapable of perceiving a changing thing without something that was changeless. Hence this is a necessary condition of knowledge. Now, let us see whether this condition can be rendered objective. According to our author it cannot, for if we subtract from surrounding things all the phenomena that fall under the domain of the senses, what remains? Nothing. Common-sense, indeed, believes in substance, but does not mean thereby an abstract and metaphysical entity, it means the whole of what strikes the senses; when the phenomenon is opposed to substance nothing is meant but that a new phenomenon has just added itself to preceding ones. Wood burns; here wood is the substance, combustion the phenomenon. This is how common-sense understands the matter; but if we separate from the idea of wood all that characterizes it as wood, nothing remains but a pure abstraction, of which common-sense takes no account, and has never so much as thought. Our author further combats the idea of substance by appealing to the metaphysical difficulties that it suggests. Is there