Down to the end of the eighteenth century world-building had been a purely speculative undertaking. It lacked actuality; it was concerned with operations thought of as belonging exclusively to a past order of things, now over and done with, and lying wholly outside the range of experience. Through Herschel's synthesis, however, those dimly apprehended operations were brought into view as variously progressing even now in different parts of the cosmos, as incipient in some regions, far advanced in others, the rubbish of the workshop here half masking the rising edifice, while elsewhere signs of decay and exhaustion give legible presage of an appointed end. And this stupendous vision of a forming universe has not vanished on critical scrutiny. It is no dream-tissue; it cannot dissolve into airy nothingness; it is based upon a firm substratum of reality. The immeasurable purposes of creative wisdom are still only in part fulfilled. It has become the strange privilege of humanity to contemplate from its little shoal of time the oceanic flow of their development. Thus, in the swing of the ages, Laplace's thought was caught up and vitalized. He himself was scarcely sensible of their movement. He recognised very imperfectly, if at all, his obligations to Herschel's nebulous star. His means were inadequate; his field of view narrow; his knowledge, though co-extensive with that of his time, fell short of what his boundless task demanded. In some respects his mode of procedure was faulty; his forecasts have been belied; the behaviour imputed by him to a nebula such as he devised is questionable, if not impossible. But with the instinct of consummate intelligence he hit off the 'psychological moment,' and, divining the genetic import of harmonies of construction obvious to perception, but arduous of interpretation, he laid down with masterly simplicity the ground-plan of a structure likely to maintain its substantial integrity despite innumerable additions and rectifications. FOOTNOTES: [Footnote 3: Quoted by Dr. Hastie in the preface to his translation of Kant's _Cosmogony_, Glasgow, 1900.] [Footnote 4: _Sur l'Origine du Monde_, 3e éd., p. 136.] [Footnote 5: This also was pointed out by M. Faye, _loc. cit._, p. 150.] [Footnote 6: _Nature_, July 9, 1903.] [Footnote 7: Rutherford, _Radio-activity_, p. 342.] [Footnote 8: _Philosophical Transactions_, vol. lxxxi., p. 85.] [Footnote 9: Herschel met Laplace during a visit to Paris in July, 1801, but what passed between them is unrecorded. In the sixth edition, however, of the _Exposition du Système du Monde_, Laplace referred to Herschel's observations of nebulæ as confirmatory of his own genetic scheme.] CHAPTER III CRITICISMS OF THE NEBULAR HYPOTHESIS