before another particle was gathered.  But the fact that so many fires which we know to be of brief duration are scattered through a region of space, and the fact of a configuration which we believe to be a transitory ore, suggest their simultaneous aggregation here and there.  And in the nebulous wreaths situated amidst the stars there is evidence that these actually originated where they now are, for in such no relative motion, I believe, has as yet been detected by the spectroscope.  All this, too, is in keeping with the nebular hypothesis of Kant and Laplace so long as this does not assume a primitive infinite dispersion of matter, but the gathering of matter from finite distances first into nebulous patches which aggregating with each other have given rise to our system of stars.  But if we extend this hypothesis throughout an infinite past by the supposition of aggregation of infinitely remote particles we replace the simultaneous approach required in order to accotnt for the simultaneous phenomena visible in the heavens, by a succession of aggregative events, by hypothesis at intervals of nearly infinite duration, when the events of the universe had consisted of fitful gleams lighted after eternities of time and extinguished for yet other eternities.

Finally, if we seek to replace the eternal instability involved in Kant’s hypothesis when extended over an infinite past, by any hypothesis of material stability, we at once find ourselves in the difficulty that from the known properties of matter such stability must have been

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permanent if ever existent, which is contrary to fact.  Thus the kinetic inertia expressed in Newton’s first law of motion might well be supposed to secure equilibrium with material attraction, but if primevally diffused matter had ever thus been held in equilibrium it must have remained so, or it was maintained so imperfectly, which brings us back to endless evolution.

On these grounds I contend that the present gravitational properties of matter cannot be supposed to have acted for all past duration.  Universal equilibrium of gravitating particles would have been indestructible by internal causes.  Perpetual instability or evolution is alike unthinkable and contrary to the phenomena of the universe of which we are cognisant.  We therefore turn from gravitating matter as affording no rational account of the past.  We do so of necessity, however much we feel our ignorance of the nature of the unknown actions to which we have recourse.

A prematerial condition of the universe was, we assume, a condition in which uniformity as regards the average distribution of energy in space prevailed, but neterogeneity and instability were possible.  The realization of that possibility was the beginning we seek, and we today are witnesses of the train of events involved in the breakdown of an eternal past equilibrium.  We are witnesses on this hypothesis, of a catastrophe possibly confined to certain regions of space, but which is, to the motions and configurations concerned, absolutely unique, reversible to