'However opinions may diverge in the detail, atomism ultimately amounts to regarding all sensory qualities, such as: tone, warmth, light, scent, and so on, indeed, if one considers the way thermodynamics derives Boyle's law, even pressure, as mere semblance, mere function of the world of atoms. Only the atom counts as ultimate factor of reality. To be consistent, one must now deny it every sensory quality, because otherwise a thing would be explained out of itself. One did, to be sure, when one set about to build up an atomistic world system, attribute to the atom all kinds of sensory qualities, albeit only in quite meager abstraction. One regards it, now as extended and impenetrable, now as mere energy center, etc. But thereby one committed the greatest inconsistency, and showed that one had not considered the above, which shows quite clearly that no sensory characteristics whatsoever may be attributed to the atom at all. Atoms must have an existence inaccessible to sensory experience. On the other hand, though, also, they themselves, and also the processes occurring in the world of atoms, especially movements, are not supposed to be something merely conceptual. The concept, after all, is something merely universal, which is without spatial existence. But the atom is supposed, even if not itself spatial, yet to be there in space, to present something particular. It is not supposed to be exhausted in its concept, but rather to have, beyond that, a form of existence in space. With that, there is taken into the concept of the atom a property that annihilates it. The atom is supposed to exist analogously to the objects of outer perception, yet not be able to be perceived. In its concept, viewability is at once affirmed and denied.
'Moreover, the atom proclaims itself right away as a mere product of speculation. When one leaves out the previously mentioned sensory qualities quite unjustifiably attributed to it, nothing is left for it but the mere “Something,” which is of course unalterable, because there is nothing about it, so nothing can be destroyed, either. The thought of mere being, transposed into space, a mere thought-point, basically just the arbitrarily multiplied Kantian “thing in itself,” confronts us.
'Against this, one could perhaps object that after all it is all the same what is understood by Atom, that one should let the scholar of natural history go ahead and operate with it — for in many tasks of mathematical physics, atomistic models are indeed advantageous —; that after all, the philosopher knows that one is not dealing with a spatial reality, but with an abstraction, like other mathematical notions. To oppose the assumption of the atom in this respect would indeed be mistaken. But that is not the issue. The philosophers are concerned with that atomism for which atom and causality are the only possible motivating forces of the world, which either denies all that is not mechanical, or else holds it to be inexplicable, as exceeding our cognitive ability. It is one thing to view the atom as a mere thought-point, another thing to want to see in it the fundamental principle of all existence. The former standpoint never goes beyond mechanical nature with it; the second holds everything to be a mechanical function.'