One important incident of the new science was the destruction of the idea that the earth is the centre of the universe. When the idea of a fixed centre went, there went with it the idea of a closed universe and a circumscribing heavenly boundary. To the Greek sense, just because its theory of knowing was dominated by esthetic considerations, the finite was the perfect. Literally, the finite was the finished, the ended, the completed, that with no ragged edges and unaccountable operations. The infinite or limitless was lacking in character just because it was in-finite. Being everything, it was nothing. It was unformed and chaotic, uncontrolled and unruly, the source of incalculable deviations and accidents. Our present feeling that associates infinity with boundless power, with capacity for expansion that knows no end, with the delight in a progress that has no external limit, would be incomprehensible were it not that interest has shifted from the esthetic to the practical; from interest in beholding a harmonious and complete scene to interest in transforming an inharmonious one. One has only to read the authors of the transition period, say Giordano Bruno, to realize what a pent-in, suffocating sensation they associated with a closed, finite world, and what a feeling of exhilaration, expansion and boundless possibility was aroused in them by the thought of a world infinite in stretch of space and time, and composed internally of infinitesimal infinitely numerous elements. That which the Greeks withdrew from with repulsion they welcomed with an intoxicated sense of adventure. The infinite meant, it was true, something forever untraversed even by thought, and hence something forever unknown--no matter how great attainment in learning. But this "forever unknown" instead of being chilling and repelling was now an inspiring challenge to ever-renewed inquiry, and an assurance of inexhaustible possibilities of progress.