HUMAN NATURE A SUBJECT OF SCIENCE. 493 



of the causes which affect the phenomenon in all 

 cases, and in a considerable degree; while others 

 which affect it in some cases only, or, if in all, only 

 in a slight degree, have not yet been sufficiently ascer- 

 tained and studied to enable us to lay down their 

 laws; still less to deduce the completed law of the 

 phenomenon, by compounding the effects of the greater 

 with those of the minor causes. Tidology, therefore, 

 is not yet an exact science; not from any inherent 

 incapacity of being so, but from the difficulty of ascer- 

 taining with complete precision the real derivative 

 uniformities. By combining, however, the exact laws 

 of the greater causes, and of such of the minor ones 

 as are sufficiently known, with such empirical laws 

 or such approximate generalizations respecting the 

 miscellaneous variations as can be obtained by spe- 

 cific observation, we can lay down general proposi- 

 tions which will be true in the main, and upon which, 

 with allowance for the degree of their probable in- 

 accuracy, we may safely ground our expectations and 

 our conduct. 



2. The science of human nature is of this de- 

 scription. It falls far short of the standard of exact- 

 ness now realized in Astronomy; but there is no 

 reason that it should not be as much a science as 

 Tidology is, or as Astronomy was when its calcula- 

 tions had only mastered the main phenomena, but not 

 the perturbations. 



The phenomena with which this science is con- 

 versant being the thoughts, feelings, and actions of 

 human beings, it would have attained the ideal per- 

 fection of a science if it enabled us to foretel how an 

 individual would think, feel, or act, throughout life, 

 with the same certainty with which astronomy enables 



