There is one portion of Fechner's theory as above stated (its metaphysical phases being beyond the scope of the present chapter have not been touched upon) that raises a question which may perhaps appear to have in itself no special significance, but which nevertheless opens up, by its implications, new fields of inquiry, and may possibly lead to further theory. The condition of stability which evolution in the universe as a whole gradually approaches but can never attain to in finite time is declared, namely, to be one not of rest, but of motion. A question might be raised, here, as to the definition of the "infinite time" asserted to be necessary to the attainment of such full stability,--whether the phrase be used in the mathematical or the philosophic sense; and the question would be found, I believe, to involve the unanswerable problem of the finite or infinite character of the universe in space. Of a universe conceived under the philosophic concept of spatial infinitude, obviously no final state as the result of evolution can be predicated, the evolution supposing a progress which, as involving infinite matter, cannot be accomplished in finite time. If we, however, conceive the universe as occupying finite space and undergoing continual evolution as a whole in the direction of equilibrium, it is a question whether the end must not be attained in finite time. For a universe conceived as finite, however immense, there must be a finite number, however great, representing the changes necessary to the attainment of final equilibrium; and if progress in the direction of such equilibrium is of necessity continual, the final equilibrium must be attainable in finite time. The question of the nature of such a state of final, universal stability is bound up with the problem of motion through a perfect void, and of the possibility of the formation of such a void through the concentration of matter. Leaving out of consideration the problem in its metaphysical form, which concerns the possibility of conceiving inter-material space, it may be said that it is not now supposed that the heavenly bodies move through an absolute void; and the existence of any medium opposing resistance, however slight, is a condition rendering impossible the attainment of absolute stability of motion or a full stability which suffers no diminution and is, therefore, in effect, an absolute stability. It may be questioned whether the very nature of motion is not coincident with change, and this with action and reaction, or competition. Such a view would reduce evolution to a single ultimate principle, in place of Darwin's Variation and Selection through struggle, or Petzoldt's Tendency and Competition. We should have left, instead of these, only the final principle involved in moving matter considered in its ultimate parts. The metaphysical problem of the infinite divisibility of matter need not here concern us; the ultimate parts of an organism could not