x VOLITION: LIBERTY AND NECESSITY 217 



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, gene- 

 rosity, public spirit : these passions, mixed in various de- 

 grees, and distributed through society, have been, from the 

 beginning of the world, and still are, the source of all the 

 actions and enterprises which have ever been observed 

 among mankind. Would you know the sentiments, incli- 

 nations, 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 transferring 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 discover 

 the constant and universal principles of human nature, by 

 showing men in all varieties of circumstances and situ- 

 ations, 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 natural philosopher be- 

 comes 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 



