86 PREFACE TO 



unwillingness openly to reveal his method Bacon coincided with 

 the common feeling of his own and earlier times. In the middle 

 ages no new discovery was freely published. All the secrets, 

 real or pretended, of the alchemists were concealed in obscure 

 and enigmatic language ; and to mention a well-known instance, 

 the anagram in which Roger Bacon is supposed to have re- 

 corded his knowledge of the art of making gunpowder is so 

 obscure, that its meaning is even now more or less doubtful. 

 In Bacon's own time one of the most remarkable discoveries of 

 Galileo that of the phases of Venus was similarly hidden in 

 an anagram, though the veil in this case was more easily seen 

 through. This disposition to conceal scientific discoveries and 

 methods is connected with the views which in the middle ages 

 were formed of the nature of science. To know that which 

 had previously been unknown was then regarded as the result 

 not so much of greater industry or acuteness as of some fortu- 

 nate accident, or of access to some hidden source of infor- 

 mation : it was like finding a concealed treasure, of which the 

 value would be decreased if others were allowed to share in 

 it. Moreover the love of the marvellous inclined men to be- 

 lieve in the existence of wonderful secrets handed down by tra- 

 dition from former ages, and any new discovery acquired some- 

 thing of the same mysterious interest by being kept back from 

 the knowledge of the vulgar. Other causes, which need not 

 here be detailed, increased this kind of reserve ; such as the 

 dread of the imputation of unlawful knowledge, the facility 

 which it gave to deception and imposture, and the like. 



The manner in which Bacon proposed at one time to per- 

 petuate the knowledge of his method is also in accordance with 

 the spirit of the middle ages. In the writings of the alchemists 

 we meet continually with stories of secrets transmitted by their 

 possessor to one or more disciples. Thus Artefius records the 

 conversation wherein his master, Boemund, transmitted to him 

 the first principles of all knowledge ; and it is remarkable that 

 in this and similar cases the disciple is called " mi fili " by his 

 instructor a circumstance which shows from what source Bacon 

 derived the phrase " ad filios," which appears in the titles of several 

 of his early pieces. Even in the De Augmentis the highest and 

 most effectual form of scientific teaching is called the " methodus 

 i/ ad filios." 1 



1 Lib. vi. c. 2. I cannot think however that the merit of this method ha;l any- 



