136 ADVANCEMENT OP LEARNING. [BOOK nr. 



like so nlttiiy sponges, which perpetually suck and draw to 

 themselves the increases of knowledge ; whence those things 

 which would have been slightly passed over, unless they had 

 been doubted of before, come now from this very doubting 

 to be more attentively considered. But these two advantages 

 will scarce balance this single inconvenience, unless well pro 

 vided against ; viz., that when a doubt is once admitted for 

 just, and becomes, as it were, authentic, it presently raises 

 up disputants on both sides, who transmit to posterity the 

 same liberty of doubting still ; so that men seem to apply their 

 wits rather to nourish, the doubt than solve it. And of this 

 we everywhere meet with examples in lawyers and scholars ; 

 who, when a doubt once gains admittance, would have it 

 remain a doubt for ever, and engage themselves in doubting 

 as well as asserting ; whereas the true use of wit is to 

 render doubtful things certain, and not certain ones doubt 

 ful. And therefore I set down as wanting a calendar of 

 doubts or problems in nature, and recommend it to be under 

 taken, with care to blot out daily, as knowledge increases, 

 those that are clearly discussed and settled. And this calen 

 dar we would have attended with another of no less utility ; 

 for as in every inquiry there are things plainly true, things 

 doubtful, and things plainly false, it were exceeding proper 

 that along with a calendar of doubts should go a calendar of 

 falsehoods and vulgar errors, both in natural history and 

 opinions, that they may no longer disturb the sciences. 



As to the opinions of the ancient philosophers, for example 

 those of Pythagoras, Philolaus, Xenophanes, Anaxagoras, 

 Parmenides, Leucippus, Democritus, and others, which men 

 usually pass slightly over, it is proper to cast a modest eye 

 upon them. For though Aristotle, after the Ottoman 

 manner, thought he could not reign secure without putting 

 all his brethren to death, yet those who do not affect 

 dominion and rule, but the inquiry and illustration of truth, 

 will find their account in beholding, at one view, the different 

 opinions of different philosophers, as to the nature of things. 

 But there is no room to expect any pure truth from these or 

 the like theories : for as the celestial appearances are solved 

 both upon the suppositions of Ptolemy and Copernicus ; so 

 common experience, and the obvious face of things, may bo 

 applied to many different theories : whilst a much stricter 



