ADVANCEMENT OF LEARNING 195 



ant, in amber; a flower, an apple, etc., in conservatories 

 of snow; or a corps of balsam; by repair, as in flame and 

 mechanic engines. He who attempts to prolong life, must 

 practice both these methods together; for separate, their 

 force is less. The human body must be preserved as bodies 

 inanimate are; again, as flame; and lastly, in some measure 

 as machines are preserved. There are, therefore, three in 

 tentions for the prolongation of life; viz., 1, to hinder 

 waste; 2, secure a good repair; and 3, to renew what begins 

 to decay. I. Waste is caused by two depredations; viz., 

 that of the internal spirit, and that of the external air; and 

 both are prevented two ways; viz., by making these agents 

 less predatory, or the patients, that is the juices of the body, 

 less apt to be preyed on. The spirit is rendered less preda 

 tory, if either its substance be condensed; as, 1, by the use 

 of opiates, preparations of nitre, and in contestation; or, 2, 

 if it be lessened in quantity, as by fasting and diet; and 

 3, if it be moderated in its motion, as by rest and quiet. 

 The ambient air becomes less predatory, either when it is 

 less heated by the sun, as in the cold countries, caves, hills; 

 or kept from the body, as by close skins, the plumage of 

 birds, and the use of oil and unguents, without spices. The 

 juices of the body are rendered less subject to be preyed on, 

 if made more hardy, or more oleaginous, as by a rough 

 astringent diet, living in the cold, robust exercises, the use 

 of certain mineral baths, sweet things, and abstaining from 

 such as are salt or acid; but especially by means of such 

 drinks as consist of subtile parts, yet without acrimony 

 or tartness. II. Eepair is procured by nourishment, and 

 nourishment is promoted four ways: 1, by forwarding in 

 ternal concoction, which drives forth the nourishment, 

 as by medicines that invigorate the principal viscera; 2, 

 by exciting the external parts to attract the nourishment, 

 as by exercise, proper frictions, unctions, and baths; 3, by 

 preparing the aliment itself, that it may more easily insin 

 uate, and require less digestion; as in many artificial ways 

 of preparing meats, drinks, bread, and reducing the effects 



