“And so while all transformations of energy lead directly or indirectly to transformation into heat, from that transformation there is no complete return, and, therefore finally no return at all. This then is the conclusion to which Mr. Spencer’s premises lead. Two eminent physicists who accept those premises may be cited at this point: ‘It is absolutely certain,’ they say, ‘that life, so far as it is physical, depends essentially upon transformations of energy; it is also absolutely certain that age after age the possibility of such transformations is becoming less and less; and, so far as we yet know, the final state of the present universe must be an aggregation (into one mass) of all the matter it contains, _i. e._ the potential energy gone, and a practically useless state of kinetic energy, _i. e._ uniform temperature throughout that mass.... The present visible universe began in time and will in time come to an end’” (p. 194). Mark now, however, that this opinion of “two eminent physicists,” quoted to disprove my position, and tacitly assumed to have validity in so far as it serves that end, is forthwith dismissed as having, for other purposes, no validity. His next paragraph runs:-- “To this conclusion we are surely led from such premises. But again I ask what warrant is there for the premises? Our experience certainly does not embrace the totality of things, is, in fact, ridiculously far from it. We have no evidence of definite space or time limits; quite the contrary. Every advance of knowledge only opens up new vistas into a remoter past and discloses further depths of immensity teeming with worlds.” Thus the truth urged against me is that we can not know anything about these ultimate physical principles in their application to the ultra-visible universe. But, unhappily for Professor Ward’s criticism, I entered this same caveat long ago. Demurring to that doctrine of the dissipation of energy to which he now demurs, I wrote:--