PHILOSOPHICAL SOCIETY OP WASHINGTON. 163 



The general mental qualification necessary for scientific ad- 

 vancement is that which is usually denominated "common sense," 

 though, added to this, imagination, invention, and trained logic, 

 either of common language or of mathematics, are important ad- 

 juncts. Nor are objects of scientific culture difficult of attain- 

 ment. It has been truly said that the " seeds of great discove- 

 ries are constantly floating around us, but that they only take root 

 and germinate in minds well prepared to receive them." 



The preparation, however, is not difficult, and many possess 

 the requisites in an eminent degree who are not aware of the fact. 

 Genius itself has been defined as a mind of general powers deter- 

 mined, enthusiastically it may be, on one pursuit. 



The method of discovery or scientific observation is not diffi- 

 cult. There is a story in a work, entitled "Evenings at Home," 

 which produced an indelible impression on my mind. It is en- 

 titled " Eyes and no Eyes," and related to two boys who started 

 on a walk during a warm summer afternoon. On their return, 

 one was fatigued, dissatisfied, having seen nothing, encountered 

 only dust aud heat, while the other was charmed with his walk, 

 which had been over the same ground, and gave a glowing ac- 

 count of the objects which he had met with, and of the reflections 

 which were awakened by them. On this story, De la Beche has 

 founded a work, entitled "How to Observe in Geology," which I 

 would commend to the attention of every member of this Society, 

 while I suggest that good service would be done to the advance 

 of knowledge were a similar work published relative to all 

 branches of science. 



The first requisite for an observer is, that his mind should be 

 actively awakened to the phenomena of nature with which he is 

 surrounded. Thousands of persons of excellent mental capacity 

 pass through the world without giving the slightest attention to 

 the ever-varying exhibitions which are presented to them. The 

 sun rises and sets, the seasons change, the heavens every night 

 present new aspects, but these to them are matters of course ; 

 they excite no interest, and it is only when some extraordinary 

 phenomenon occurs, such as the blazing comet or the startling 

 earthquake, that their attention is arrested. Another requisite is 

 the power of the perception of truth, which enables the observer 

 to recognize and define with unerring accuracy what he has seen 

 without any tinge of color from d, priori conceptions. Still an- 



