The hypothetical and problematical nature of the theory of atoms strikes us still more clearly when we try to analyze it philosophically. First, we meet that antinomy which we always find where we try to pass beyond the limits of our empirical knowledge by means of conception. For, if the atoms still occupy space, we can not understand why they should not be further divisible, and if they do not occupy space, we can not understand how any sum of that which does not occupy space, can finally succeed in filling space. It is true, this very antinomy has led to the overcoming of that dualism of force and matter which so long enchained science, and the overcoming of which we greet as a progress of our theoretical knowledge of nature. We no {144} longer look upon the atoms as material elements, but as centres of force. The antinomy has the further merit that, in the realm of the knowledge of nature, it brings to our consciousness the great advantage of a concrete perception and reasoning over purely logical abstractions. For Ulrici, in his "God and Nature," is right in calling our attention to the fact that we must think about the atoms, not in an _abstractly_ logical and an _abstractly_ mathematical way, but concretely; that we have to consider them, not as mere quantities, but as qualities; and that we can then easily arrive at the perception of something which occupies space, and which therefore, according to abstract conclusions of logic and mathematics, could still be thought of as divisible _in abstracto_, but which, even as a consequence of its _quality_, of its concrete natural form, is no longer divisible in reality. Nevertheless, in spite of all these remarkable attempts at overcoming the difficulties of the theory of atoms, that antinomy returns as often as we undertake to make that clearly perceptible which we have at last gained a partial conception of; and thus shows us, from this side also, that even with the theory of atoms we have arrived at the limit where not only our observation, but also the preciseness and certainty of our conceptions, ceases.