88 THE HISTORY OF BIOLOGY 



sentences; under its guidance human thought has been led into delusions, 

 which are classified under four different categories denoted by the names 

 "idols of the tribe," "of the cave," "of the market-place," and "of the 

 theatre." By idols of the tribe are meant those fallacies which are incident 

 to human nature, man's tendency to interpret the phenomena of nature ac- 

 cording to human preconceptions. The idols of the cave are man's individual 

 tendency to judge according to his own person or ego; it is as if a man sat in 

 a cave and from there saw things in a one-sided light. The idols of the mar- 

 ket-place are fallacies which arise out of human community-life, especially 

 errors arising from the influence exercised over the mind by mere words, 

 the confusing influence of traditional nomenclature upon the idea of things. 

 Finally, the idols of the theatre are those which are induced by the power of 

 tradition and result from received systems of philosophy and the tendency 

 of their theory to captivate the senses. The criticism which in further de- 

 veloping these principles he directs against the philosophy of his time is in 

 many cases extraordinarily sharp and holds good for every age. Thus he 

 utters insistent warnings against the common tendency to regard natural 

 phenomena as simple mechanical constructions, like those which man him- 

 self puts together and takes to pieces. Nature is, on the contrary, extremely 

 complicated and one must be. careful how one ascribes to its course of events 

 the same order and regularity which man loves to ordain for himself. From 

 this error arise fallacies such as the idea that the orbits of the heavenly 

 bodies must necessarily be circular, just because the circle is the most regular 

 figure. In contrast to the artificial and false idea of nature which the old 

 philosophy creates by means of such modes of thought. Bacon sets up the 

 true knowledge of nature, which is acquired by observation and experiment. 

 Man overcomes nature by obeying her laws and learns to understand her by 

 putting proper questions to her. Thus one arrives at the true scientific 

 method, that which by careful observation of the peculiarities of existence 

 and by a classification of them acquires knowledge of the general laws of 

 nature. Bacon attaches the very highest hopes to the value of the knowledge 

 of nature which he thus intended to create; throughout his long life he never 

 ceased to contemplate with passionate enthusiasm the thought of the ex- 

 traordinary life-values which awaited the human spirit in an enhanced 

 knowledge of the true essence of nature. Such knowledge could be attained 

 by means of a schematic procedure laid down once and for all, applicable 

 equally to high and low in the realm of thought. To this art of deduction, 

 however, based on a consideration of the temporal sequence of phenomena, 

 their presence and absence, and their numerical relations. Bacon gave a value 

 which it did not possess, and besides applied it in a manner which led to 

 sheer absurdities. His knowledge of nature, moreover, was limited and by 

 no means unprejudiced — he was, for instance, in opposition to Copernicus — 



