To this we may reply, that after all it does not do to draw straightaway a strict parallel between social and natural processes. Unconsciously, of course, our conception of the one will influence our conception of the other, as we have just seen, but that is by no means an advantage, and our duty with regard to the direct transference of the laws from one domain to the other is not to encourage it consciously, but rather to discourage. Every advance in the methods of observation, and in the proper understanding of one sphere may, and will certainly, help on our methods and our understanding of others, but equally certain it is, that each of these spheres is governed by its own peculiar laws, which to the other have no application.
Even between animate and inanimate nature a sharp distinction must be drawn, and no one would dream, on the ground of a mere outward similarity, of applying without any further consideration a law that operates in one sphere to the other; for example, to solve the problems of sexual propagation and inheritance simply by the laws of chemical combinations. An equally serious mistake, however, is made when the laws of external nature are directly applied to society, as, for example, when competition, on the strength of the struggle for existence, is proclaimed a natural necessity, or the reprehensibility or the impossibility of the social revolution is deducted from laws of evolution in nature.
One may go, however, still further. If the old catastrophic theories in natural science are gone for ever, the new theories which see in evolution only the accumulation of infinitesimal and imperceptible changes meet also with an ever stronger opposition. On the one hand, increases predilection for quiet, for conservative theories which reduce evolution itself to a negligible quantity; on the other hand, facts make it imperative again to accord to catastrophic changes a larger part in the natural development. This applies equally to Lyell's theories of geological, and to Darwin's theory of organic, evolution.
There is thus being formed a kind of a synthesis of the old catastrophic and the modern evolutionary theories analogous to that which they have found in Marxism. Just as the latter distinguishes between the gradual economic development and the more rapid transformation of the juridical and political superstructure, so many of the latest biological and geological theories recognise along with the slow accumulation of small and fractional changes, also sudden and far-reaching changes of form—catastrophic changes—which proceed from the former.
As a remarkable example of this we may quote the observations which De Vries communicated to the last congress of natural scientists in Hamburg. He had found that the plant and animal species remain for a long time unchanged; some finally disappear, when they become old and unfit for the conditions of life which have in the meantime altered. Others are more successful,
