intellect; to this poor material, then, it finds itself reduced for the construction of its castle in the air. In this way it inevitably becomes _atomism_; as happened to it already in its childhood in the hands of Leucippus and Democritus, and happens to it again now that it has come to a second childhood through age; with the French because they have never known the Kantian philosophy, and with the Germans because they have forgotten it. And indeed it carries it further in this its second childhood than in its first. Not merely _solid_ bodies are supposed to consist of atoms, but liquids, water, air, gas, nay, even light, which is supposed to be the undulations of a completely hypothetical and altogether unproved ether, consisting of atoms, the difference of the rapidity of these undulations causing colours. This is an hypothesis which, like the earlier Newtonian seven‐colour theory, starts from an analogy with music, entirely arbitrarily assumed, and then violently carried out. One must really be credulous to an unheard‐of degree to let oneself be persuaded that the innumerable different ether vibrations proceeding from the infinite multiplicity of coloured surfaces in this varied world could constantly, and each in its own time, run through and everywhere cross each other without ever disturbing each other, but should rather produce through such tumult and confusion the profoundly peaceful aspect of illumined nature and art. _Credat Judæus Apella!_ Certainly the nature of light is to us a secret; but it is better to confess this than to bar the way of future knowledge by bad theories. That light is something quite different from a mere mechanical movement, undulation, or vibration and tremor, indeed that it is material, is shown by its chemical effects, a beautiful series of which was recently laid before the _Académie des sciences_ by Chevreul, who let sunlight act upon different coloured materials. The most beautiful thing in these experiments is, that a white roll of paper which has been exposed to the sunlight exhibits the same effects, nay, does so even after six months, if during this time it has been secured in a firmly closed metal tube. Has, then, the tremulation paused for six months, and does it now fall into time again? (_Comptes rendus_ of 20th December 1858.) This whole hypothesis of vibrating ether atoms is not only a chimera, but equals in awkward crudeness the worst of Democritus, and yet is shameless enough, at the present day, to profess to be an established fact, and has thus brought it about that it is orthodoxly repeated by a thousand stupid scribblers of all kinds, who are devoid of all knowledge of such things, and is believed in as a gospel. But the doctrine of atoms in general goes still further: it is soon a case of _Spartam, quam nactus es, orna_! Different perpetual motions are then ascribed to all the atoms, revolving, vibrating, &c., according to the office of each; in the same way every