however that the matter cannot be definitely determined by mere speculative generalizations; genuine proof can only come from the discovery of new facts of experience. And he believes furthermore, and rightly so, that no one can investigate the matter without prejudice who adheres dogmatically to the traditional hypothesis.—At one important point he was able to appeal to well-defined facts. He rejected the theory, still accepted by Copernicus, that the stars are enclosed in permanent spheres: If the earth can move freely in space, why should it be impossible for the stars to do the same? And he found his conclusion verified by Tycho Brahe’s investigation of comets, which as a matter of fact pass diagonally through the “Spheres” whose crystal masses were supposed to separate the various parts of the universe! It follows therefore that the contrast of heaven and earth, of permanent and changeable parts of the universe, is untenable.
b. In his philosophy of religion Bruno starts with the infinitude of the Deity. But if the cause or principle of the universe is infinite it must follow that the universe itself is likewise infinite! We are unable to believe that the divine fullness could find expression in a finite universe; nothing short of an infinite number of creatures and worlds would be an adequate display of such fullness.
Bruno elaborated his theory of the infinity of the universe in two dialogues, the Cena de la ceneri and Del’ infinito universo e mondi (1584), and in the Latin didactic poem De immenso (1591). These works are of epochal importance in the history of the human mind. Just as this wide expanse inspired in Bruno a feeling akin to deliverance from the confines of a narrow cell, so the human mind is now presented with a boundless