was this same feeling, doubtless, which suggested to Bacon the oft-repeated maxim that induction should proceed from particulars to axioms of a very low degree of generalisation (axiomata infima), and thence slowly and gradually, through successive stages of intermediate axioms (axiomata media), up to the highest axioms of all (axiomata maxime generalia), and that we should never arrive at these last, or indeed at any axioms of any high degree of generality, by sudden leaps. But this method of gradual and continuous ascent is not the method which, for the most part, has been actually pursued by the most successful interrogators of nature. Though a more ambitious process is a common and a perfectly legitimate method of discovery, the proof of the higher axioms, when established, will generally be found to rest on intermediate axioms, and of these on still lower axioms, and so on, after the manner which Bacon describes. Moreover, when a science has attained anything like completeness, this will always be found to be the most convenient method of exhibiting the relation of its various laws. Though stated too exclusively, therefore, this part of Bacon's doctrine is by no means so untrue to facts or to the reason of the thing as it has sometimes been represented to be.
One of the main peculiarities of Bacon's system was his rejection of the inquiry into final causes, a characteristic of his philosophy for which he has often been severely censured. But it should be noted in the first place that he did not propose to banish this inquiry altogether, but to relegate it from physic, which he supposed to be concerned solely with material and efficient causes, to what he called metaphysic, which was to inquire into formal and final causes, and which would include what we now call natural theology.
It must be admitted that Bacon was not fully abreast of the scientific knowledge of his own day. Much is doubtless to be said in extenuation, but an impartial judge can only advise a plea of 'guilty' on many of the counts in the indictment. He makes no mention, for instance, of Harvey's great discovery of the circulation of the blood, though Harvey had already begun to teach it in 1619, the year before the appearance of the 'Novum Organum.' Bacon appears never to have heard of the astronomical discoveries recently made by means of Kepler's calculations, and he was singularly ignorant of many facts both in the theory and the history of mathematics and mechanics. But far the most important and perhaps, at first sight, the least excusable of his scientific errors was his persistent rejection of the Copernican theory. It seems indeed strange that one who laid claim to be the great reformer of science should have steadily refused to admit the greatest reform in scientific conceptions which had been proposed for many generations, and which had already been before the world for eighty years. And, undoubtedly, the discovery by Galileo of the satellites of Jupiter in 1609, as well as the calculations of Kepler announced about the same time (with which last, however. Bacon does not seem to have been acquainted), had considerably added to the evidence in favour of the heliocentric system, even while the 'Novum Organum' was being written. Still, it cannot be said that, till the laws of formal astronomy were connected by Newton with the physical laws of matter and motion, the motions of the earth or its relation to the rest of the solar system could in any way be regarded as placed beyond the range of dispute. And Bacon certainly did not stand alone in his opposition among the eminent men of that age. Among those of his contemporaries who rejected the Copernican theory were Tycho Brahé (who, however, died in 1601), Vieta, the greatest mathematician of the sixteenth century (who also died as early as 1603), Clavius, who was employed by Gregory XIII to reform the Calendar and was called the Euclid of his age, and possibly, from his silence, the famous mechanician Stevinus.
It would be an injustice to Bacon not to notice that, even in the particular sciences, he threw out many suggestions of rare sagacity, and, in a certain sense, anticipated more recent discoveries. Such were his speculations on colour, his anticipation of the recent theory of heat, his experiment on the compressibility of water, and his wonderful appreciation of the combined unity and variety in nature. To these instances may be added his sagacious and possibly fertile suggestion of a closer union between formal and physical astronomy, as well as of the necessity of combining the explanations of celestial and terrestrial phenomena; the remarkable passage on Attraction, and the ingenious experiment proposed in connection with it, in 'Novum Organum' (ii. 36, 3); the brilliant conjecture, in 'Novum Organum' (ii. 46), that the actual state of the starry sky precedes by an interval of time that which is apparent to us, or, in other words, that light requires time for its transmission; the implied criticism of the ordinary doctrine of species contained in a passage on Realism in 'Novum Organum' (i. 66); and lastly (though this list is by no means exhaustive) the attempt made in the
