SCIENTIFIC CULTURE. 525 



But I must pass on to speak of the importance in the study of 

 Nature of accuracy in detail, which is the second condition of success- 

 ful observation of which I spoke. We must cultivate not only accu- 

 racy in observing details, but also accuracy in following details which 

 have been laid down by others for our guidance. In science we can- 

 not draw correct conclusions from our premises unless we are sure 

 that we have all the facts, and what seemed at first an unimportant 

 detail often proves to be the determining condition of the result ; and 

 again, if we are told that under certain conditions a certain sio-n is the 

 proof of the presence of a certain substance, we have no right to as- 

 sume that the sign is of any value unless the conditions are fulfilled. 

 A black precipitate, for example, obtained under certain conditions, is 

 a proof of the presence of nickel, but we cannot assert that we have 

 found nickel unless we have followed out those details in every partic- 

 ular. Of course, we must avoid empiricism as far as we can. We must 

 seek to learn the reasons of the details, and such knowledge will not 

 only render our works intelligent, but will also frequently enable us to 

 judge how far the details are essential, and to what extent our pro- 

 cesses may be varied with safety. We must also avoid trifling, and 

 above all " the straining at a gnat and swallowing a camel," as is the 

 habit with triflers. Large knowledge and good judgment will avoid 

 all such errors ; but, if we must choose between fussiness and careless- 

 ness, the first is the least evil. Slovenly work means slovenly results, 

 and habits of carefulness, neatness, and order, produce as excellent 

 fruits in the laboratory as in the home. 



Last in order but first in importance of the conditions of successful 

 observation, mentioned above, stands truthfulness. Here you may 

 think I am approaching a delicate subject, of which even to speak 

 might seem to cast a reproach. But not so at all. I am not speaking 

 here of conscious deception, for I assume that no one who aspires to 

 be a student of Nature can be guilty of that. But I am speaking of a 

 quality whose absence is not necessarily a mark of sinfulness, but 

 whose possession, in a high degree, is a characteristic of the greatest 

 scientific talent. As every lawyer knows, he is a rare man whose testi- 

 mony is not colored by his interests, and a very large amount of self- 

 deception is compatible with conscious honesty of purpose. So among 

 scientific students the power to keep the mind unbiased and not to color 

 our observations in the least degree, is one of the rarest as it is one of 

 the noblest of qualities. It is a quality we must strive after with all our 

 mio-ht, and we shall not attain it unless we strive. Remember, our ob- 

 servations are our data, and, unless accurate, every thing deduced from 

 them must have the taint of our deception. We cannot deceive Na- 

 ture, however much Ave may deceive ourselves ; and there is many a 

 student who would cut off his right hand rather than be guilty of a 

 conscious untruth, who is yet constantly untruthful to himself. Every 

 year students of mineralogy present to me written descriptions of 



