U^ AbVAiJCfiMEifT 01* LteAKKiKG. [feOO^ tit. 



thougli it liiay mucli more probably be effected by a man 

 acquainted Avith the nature of gravity, colour, malleability, 

 fixedness, volatility, the principles of metals and menstruums, 

 than by one who is ignorant of these natures, by the bare 

 projection of a few grains of the elixir. The same may be 

 understood of the prolongation of youth or retarding of old 

 age, which may more rationally be expected by dietary, re- 

 gimen, bathings, anointing, and proper medicines, directed 

 by an accurate knowledge of the human frame, the nature of 

 rarefaction, sustention, assimilation, and the reciprocal action 

 of the mind upon the body, than by a few drops or scruples 

 of some precious liquor or quintessence. But men are so 

 headstrong and notional, as not only to promise themselves 

 things impossible, but also hope to obtain the most difficult 

 ends without labour or exertion. 



This practical doctrine of nature requires two appendages 

 of very great consequence. The first is, that an inventory 

 be made of the stock of mankind, containing their whole 

 possessions and fortunes, whether proceeding from nature or 

 art, with the addition also of things formerly known, but 

 now lost ; so that he who goes upon new discoveries may 

 have a knowledge of what has already been done. This 

 inventory will be the more artificial and useful, if it also 

 contain things of every kind, which, according to common 

 opinion, are impossible ; as likewise such as seemed next to 

 impossible, yet have been effected, the one to whet the 

 human invention, and the other to direct it, so that from 

 these optatives and potentials actives may the more readily 

 be deduced. 



The second thing is, that a calendar be made of such ex- 

 periments as are most extensively useful, and that lead to 

 the discovery of others. For example, the experiment of 

 artificial freezing, by means of ice and bay salt, is of infinite 

 extent, and discovers a secret method of condensation of great 

 service to mankind ; fire is ready at hand for rarefaction, 

 but the means of condensation are wanted. And it would 

 greatly shorten the way to discoveries, to have a particular 

 catalogue of these leading experime uts. 



