x VOLITION: LIBERTY AND NECESSITY 215 



ever agreed in the doctrine of necessity, and that they have 

 hitherto disputed merely from not understanding each other." 

 -(IV. p. 97.) 



But is this constant conjunction observable in 

 human actions ? A student of history could give 

 but one answer to this question : 



"Ambition, avarice, self-love, vanity, friendship, generosity, 

 public spirit : these passions, mixed in various degrees, and 

 distributed through society, have been, from the beginning of 

 the world, and still are, the source of all the actions and enter- 

 prizes which have ever been observed among mankind. Would 

 you know the sentiments, inclinations, and course of life of the 

 Greeks and Romans ? Study well the temper and actions of the 

 French and English. You cannot be much mistaken in trans- 

 ferring to the former most of the observations which you have 

 made with regard to the latter. Mankind are so much the 

 same, in all times and places, that history informs us of nothing 

 new or strange in this particular. Its chief use is only to dis- 

 cover the constant and universal principles of human nature, 

 by showing men in all varieties of circumstances and situations, 

 and furnishing us with materials from which we may form our 

 observations, and become acquainted with the regular springs of 

 human action and behaviour. These records of wars, intrigues, 

 factions, and revolutions are so many collections of experiments, 

 by which the politician or moral philosopher fixes the principles 

 of his science, in the same manner as the physician or natnral 

 philosopher becomes acquainted with the nature of plants, 

 minerals, and other external objects, by the experiments which 

 he forms concerning them. Nor are the earth, air, water, and 

 other elements examined by Aristotle and Hippocrates more like 

 to those which at present lie under our observation, than the 

 men described by Polybius and Tacitus are to those who now 

 govern the world." (IV. pp. 97-8.) 



Hume proceeds to point out that the value set 

 upon experience in the conduct of affairs, whether 



