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afterwards. The necessity of strict and minute observation, then, is 

 the first thing which the student of the physical sciences has to learn ; 

 and it is easy to see with what great advantage the habit thus 

 acquired may be carried into everything else afterwards. Slovenly 

 habits of observation are indeed the source of a large proportion of 

 the evils which mankind bring upon themselves of blunders in 

 private life by which an individual causes the ruin of himself and his 

 wife and children, of blunders in statesmanship which bring cala- 

 mities on nations. It is to these, moreover, that impostors and 

 fanatics of all kinds and in all ages have been indebted for their 

 influence and success. 



It would be easy to show how in various other ways the study of 

 the physical sciences cannot fail to be a useful training for the 

 mind. Very much indeed might be said on this subject; but to 

 enter fully into it would not only occupy too much of your time, 

 but would involve us in a metaphysical discussion unsuited to the 

 present occasion. There are, nevertheless, two or three points to 

 which I shall venture, however briefly, to allude. 



Investigations of this kind, more than almost any other, impress 

 the mind with the necessity of looking carefully at both sides of a 

 question, and strictly comparing the evidence on one side with that 

 on the other ; and in this manner they help to correct and improve 

 the judgment. As in every such investigation classification is an 

 important and indeed a necessary element, another effect is that of 

 promoting and strengthening the best kind of memory a memory 

 founded on some actual relation of objects to each other, and not 

 on mere apparent resemblance and juxtaposition. Lastly, physical 

 investigations more than anything besides help to teach us the actual 

 value and the right use of the imagination, of that wondrous faculty 

 which, left to ramble uncontrolled, leads us astray into a wilderness of 

 perplexities and errors, a land of mists and shadows ; but which, 

 properly restrained by experience and reflection, becomes the noblest 

 attribute of man the source of the poetic genius, the instrument 

 of discovery in science, without the aid of which Newton would never 

 have invented fluxions, nor Davy have decomposed the earths and 

 alkalies, nor would Columbus have found another continent beyond 

 the Atlantic Ocean. 



In the pursuit of the physical sciences, the imagination supplies 



