ADVANCEMENT OF LEARNING 93 



the praises but the imitation of posterity, since new doubts are 

 daily arising. But the utmost caution is to be used in such an 

 undertaking. The recording and proposing of doubts has two 

 advantages; the one, as it defends philosophy against errors, 

 when that which is not clear is neither judged nor asserted, lest 

 error thus should multiply error, but judgment is suspended 

 upon it, and not made positive ; the other is, that doubts once 

 registered are like so many sponges, which perpetually suck 

 and draw to themselves the increases of knowledge; whence 

 those things which would have been slightly passed over, un- 

 less 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 provided 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 forever, 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 doubtful. And therefore 

 I set down as wanting a calendar of doubts or problems in nat- 

 ure, and recommend it to be undertaken, with care to blot out 

 daily, as knowledge increases, those that are clearly discussed 

 and settled. And this calendar 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 ac- 



