There is, however, a further point connected with the doctrine of energy, which deserves consideration as bearing on the tendency to anticipate an indefinite line of progression in the history of this world, that is, deterioration or degradation in the form of energy, while it continues of equal amount. The efficient value of energy is according to the possibilities of transformation or transmutation. But its use implies limitation of the available forms, or steady deterioration of value. "Thus the energy of the universe is, on the whole, constantly passing from higher to lower forms, and therefore the possibility of transformation is becoming smaller and smaller, so that after the lapse of sufficient time all higher forms of energy must have passed from the physical universe, and we can imagine nothing as remaining, except those lower forms which are incapable, so far as we yet know, of any further transformation."[AL] Such a statement of the position, though it can not be regarded as an ultimate one in scientific research, is so obviously a deduction from present knowledge that it must to some extent modify prevailing conceptions. It may, indeed be suggested that some catastrophe may terminate the present order of things, and that some action of the law of gravitation may combine the fragments of worlds, and give a fresh start with new combinations of energy; but the bare suggestion of this implies a much wider range for scientific research than any thing yet known to us, and at the same time a larger demand upon intelligence in the control and regulation of what must nevertheless seem to us violent catastrophes. Such speculation, if it may warrantably find encouragement under purely scientific conditions, religious thought will neither gainsay nor resist; but will find itself in no perplexity to accept.