SCIENTISTS OF XVrn AND XVlTH CENTURIES. 105 



(del bene intendere], and sound understanding from reason 

 (ragione}) itself born from sound experience, the common 

 mother of all the sciences and all the arts. 



"The rules of experience are sufficient means (cagioni) 

 for us to discern the true from the false. 



" Before laying down a general rule, experiment two or 

 three times, and see whether the experiments produce the 

 same effects." 



This was thought, said, written, and acted upon more than 

 a hundred years before the Novum Organum saw the light. 

 In the face of this plain and direct language it is rather 

 strange that Dr. Whewell should have dared to convey the 

 idea that the writings of those who preceded Francis Bacon 

 were "too abstruse" to be understood for the unvarnished 

 truth is that the cases are reversed. This misleading state- 

 ment has been quoted so often that it is only right we should 

 protest against it by showing its complete inaccuracy. 



Leonardo despises the Alchemists who seek the trans- 

 mutation of metals, but recognises them as fruitful inquirers 

 within certain limits that is as founders of chemistry. He 

 condemns without restriction " the searchers of perpetual 

 motion, necromancers, magicians, who beget nothing but 

 lies/' And being a real man of science he does not forget 

 the great part played by mathematics and deduction, 

 without which induction would be inefficacious. He says : 



" He who blames the supreme certainty of mathematics 

 feeds on confusion, and will never put a stop to the contra- 

 dictions of the sophistical science which produces nothing but 

 an eternal clamour (un eterno gridore). 



" Wherever there is relation and proportion, there is room 

 for calculation ; the proportion is not found in numbers 

 and measures only, but likewise in sound, gravity, time, 

 place (space), and in any force whatever." This aphorism,, 

 worthy of Newton himself, reveals a masterly insight and 

 grasp of science in its most important bearings. 



"True science," he goes on, "is not nourished by the 

 dreams of its investigators; but from the first true and 

 ascertained principles it advances progressively and with true 

 consequences to the very end. This is what we see in the 



