Truths, either ufeful to Humane Life, or improving the onder- 
ftandingof Man: But by reafon of many troublefom Avocat> 
ons, T cannot apply my felf to it but by Fits and Intervals > and 
I muft ftay for a better time, and more favourable opportunitics> 
to comply with my genius. All I can do at prefent, is, to make 
Reflexions upon fomc Experin^^ents, in the doing of which I find 
I am more particularly engaged in thofe^ which regard our health > 
concerning which, I employ much of that time I can redeem 
from thebufinefsof my^Voyages^ wherein, when I am alone, I 
frequently entertain my felf with ^^»4/ Subject. And in refe- 
rence to itj I fliall now declare unto you^ under the favour of Phi- 
lofophical liberty, and your friendfliip,a thought of mine,much 
polTeffing my mind, but perhapsone of the moft extravagant in 
the judgement of the Vulgar. 
A fter I had often refle(aed upon the general caufes of Difea- 
fes that lead to Death, I mean thofe of the Debilitation of Na- 
tures flrength inthecourfeof mans-life, until its utter extindi- 
on,andof thecaufesof a meerly natural Death, by the failure 
of that ftrengthin an extreme decrepit Age, without thj? con- 
currence of any excefs or external caufe 1 have entertained fome - 
conjeiiurej^thatif wewere more intelligent in this matter, than 
we arcj we might procure for our felv^es an Age of continual 
Youth % fetting afide the feveral Accidents of Divine Provi- 
dence, and meerly confidering the forces of Nature^ not only not 
hinder'd, but alfo afCfted as much as may be. 
A certain Philofopher hath formerly been upon the fame 
thing, and Cardan affiims, that being young, this fancy rolled in 
his head and theC^/V/^/^ fearch for it withan extreme induftry 5 
hut neither thofe, that have recorded that of the ancient Philo- 
fopher, nor Cardm^hm^idii any thing of the ground of their no- 
tion, nor cf the way which they thought w as to be obferved for 
auaining tlie end thereof, Ne mdear ir^anire fine rationcy I 
will tell yoa, what it is, I have grounded my conjeiturc 
upon. ' , . 
Searching for the true caufes of old Age, and of natural 
Death, I was not fatisfied with that extindionof natural he^t 
and cfficcntion of the Radical humour, affign'd to be the caufe 
thereof, uor with ihe caufes of this extinction and deficcation. 
