Mental niscif/int' in Intimation. 



is evident to whoever comes to the study from that of the experi- 

 mental sciences, that no political conclusions of any value lor practice- 

 can l>r arrived at by direct experience. Such specific experi'-m 

 we can have, serves only to verity, and even that insufficiently, the 

 conclusions of reasoning. Take any active force you please in poli- 

 tics, take the liberties of England, or free trade ; how should we 

 know that either of these things conduced to prosperity, if we could 

 discern no tendency in the things themselves to produce it? If we 

 had only the evidence of what is called our experience, such pros- 

 perity as we enjoy might be owing to a hundred other causes, and 

 might have been obstructed, not promoted, by these. All true 

 political science is, in one sense of the phrase, a priori, being de- 

 duced from the tendencies of things, tendencies known either through 

 our general experience of human nature, or as the result of an anal- 

 ysis of the course of history, considered as a progressive evolution. 

 It requires, therefore, the union of induction and deduction, and the 

 mind that is equal to it must have been well disciplined in both. But 

 familiarity with scientific experiment at least does the useful service 

 of inspiring a wholesome scepticism about the conclusions which the 

 mere surface of experience suggests. 



The discipline of observation and strict reasoning af- 

 forded by the exact sciences, mathematics, physics, and 

 chemistry, pure and applied, being secured, we then pass 

 to the study of the biological sciences, botany, zoology, 

 physiology, geology. A new order of truths and new cir- 

 cumstances of knowledge are here encountered, to which 

 the sciences just considered are an indispensable introduc- 

 tion, but for which, the mental habits they form are not art- 

 adequate preparation. We are still carefully to observe, 

 still to reason from facts to general principles, but the facts, 

 though equally positive, are now so different so complex, 

 inaccessible, and indefinite, as to embarrass inference, and 

 call for a higher exercise of the judgment. Experiment 

 or active observation, which plays so prominent a part in 

 physics and chemistry, is here greatly limited; we cannot 

 isolate the phenomena, and turn them round and round, 



