Alike in the details of his propaganda and in the temper of his utterance, Bruno expresses from first to last the spirit of freethought and free speech. Libertas philosophica [205] is the breath of his nostrils; and by his life and his death alike he upholds the ideal for men as no other before him did. The wariness of Rabelais and the non-committal skepticism of Montaigne are alike alien to him; he is too lacking in reticence, too explosive, to give due heed even to the common-sense amenities of life, much more to hedge his meaning with safeguarding qualifications. And it was doubtless as much by the contagion of his mood as by his lore that he impressed men.
His personal and literary influence was probably most powerful in respect of his eager propaganda of the Copernican doctrine, which he of his own force vitally expanded and made part of a pantheistic conception of the universe. [206] Where Copernicus adhered by implication to the idea of an external and limitary sphere--the last of the eight of the Ptolemaic theory--Bruno reverted boldly to the doctrine of Anaximandros, and declared firmly for the infinity of space and of the series of the worlds. In regard to biology he makes an equivalent advance, starting from the thought of Empedocles and Lucretius, and substituting an idea of natural selection for that of creative providence. [207] The conception is definitely thought out, and marks him as one of the renovators of scientific no less than of philosophic thought for the modern world; though the special paralysis of science under Christian theology kept his ideas on this side pretty much a dead letter for his own day. And indeed it was to the universal and not the particular that his thought chiefly and most enthusiastically turned. A philosophic poet rather than a philosopher or man of science, he yet set abroad for the modern world that conception of the physical infinity of the universe which, once psychologically assimilated, makes an end of the medieval theory of things. On this head he was eagerly affirmative; and the merely Pyrrhonic skeptics he assailed as he did the "asinine" orthodox, though he insisted on doubt as the beginning of wisdom.
Of his extensive literary output not much is stamped with lasting scientific fitness or literary charm; and some of his treatises, as those on mnemonics, have no more value than the product of his didactic model, Raymond Lully. As a writer he is at his best in the sweeping expatiation of his more general philosophic treatises, where he attains a lifting ardour of inspiration, a fervour of soaring outlook, that puts him in the front rank of the thinkers of his age. And if his literary character is at times open to severe criticism in respect of his lack of balance, sobriety, and self-command, his final courage atones for such shortcomings.