48 ADVANCEMENT OP LEARNIN(}. [BOOK 1. 



thouglit worth recording in a book by tlieinselves," tlius 

 wisely intimating, that matter of truth which is the basis of 

 solid experience, philosophy, and the sciences, should not 

 be mixed with matter of doubtful credit ; and yet that 

 curiosities or prodigies, though seemingly incredible, are not 

 to be suppressed or denied the registering. 



Credulity in arts and opinions, is likewise of two kinds ; 

 viz., when men give too much belief to arts thnmselves, or 

 to certain authors in any art. The sciences that sway the 

 imagination more than the reason, are principally three ; viz., 

 astrology, natural magic, and alchemy ; the ends or preten- 

 sions whereof are however noble. For astrology pretends 

 to discover the influence of the superior upon the inferior 

 bodies ; natural magic pretends to reduce natural philosophy 

 from speculation to works ; and chemistry pretends to 

 separate the dissimilar parts, incorporated in natural mix- 

 tures, and to cleanse such bodies as are impure, throw out 

 the heterogeneous parts, and perfect such as are immature. 

 But the means supposed to produce these effects are, both in 

 theory and practice, full of error and vanity, and besides, are 

 seldom delivered with candour, but generally concealed by 

 artifice and enigmatical expressions, referring to tradition, 

 and using other devices to cloak imposture. Yet alchemy 

 may be compared to the man who told his sons, he had left 

 them gold buried somewhere in his vineyard ; where they, 

 by digging, found no gold, but by turning up the mould about 

 the roots of the vines, procured a plentiful vintage. So the 

 search and endeavours to make gold have brought many 

 useful inventions and instructive experiments to light.P 



Credulity in respect of certain authors, and making them 



" Oavficicna 'KKovaixciTa. 



P As among the Egyptians, the Chinese, and the Arabians, if their 

 histories are to be credited. In later times, they make copper 

 oat of iron, at Newsohl, in Germany. See Agricola " De Re Metal- 

 lica/' Morhof, Fr. Hoffman, &c. Whilst Brand of Hamburgh w;i3 

 working upon urine, in order to find the philosopher's stone, he 

 stumbled upon that ca.lled Kunckel's burning phosphorus, in the year 

 1669. See Mem. de I'Acad. Royal, des Sciences, an 1692. And M. 

 Ilomberg operating upon human excrement, for an oil to convert quick- 

 silver into silver, accidentally produced what we now call the black 

 phosphorus, a powder which readily takes fire and burns like a coal in 

 the open air. See M^m. de I'Acad. an 1711. Tc give all the instsncot 

 « f this kind were almost endless. £d. 



