362 SPARKS FROM A GEOLOGIST'S HAMMER. 



which accumulated in the observatory of Tycho Brahe. 

 Without deduction, the universe of phenomena would pre- 

 sent the order and symmetry of a perfect machine, the 

 products of whose activity we could know only as they 

 were wrought out. Anticipation, prediction, and all 

 the plans and operations based upon expectation, would 

 have no place among human activities if science could not 

 descend from principle to fact. All conceptions' of phe- 

 nomena that have not been objects of cognition must be 

 based on deduction, proceeding from general principles 

 established by induction from cognized phenomena. By 

 such means science has affirmed the internal solidity of 

 the earth, or predicted the eccentricity of her orbit at 

 an epoch a million years in the future, or pictured her 

 physical condition in a past removed from us by millions 

 of years. 



Such seem to be the scope and prerogatives of that 

 department of science whose data are sensible phenomena. 

 The term science, in its modern, popular acceptation, 

 signifies the science of sensible phenomena. When the 

 term is employed without qualification it is generally 

 understood to signify pJnjsical science. 



There are, however, other fields of phenomena using 

 the term in an extended but legitimate sense cognizable 

 through internal, instead of external, perception. The 

 phenomena of the mind have an existence as certain, and 

 orders of succession as fixed and cognizable, as the phe- 

 nomena of the external world. The reality of mental 

 phenomena is absolutely unquestionable. They are, in 

 fact, the only data of demonstrable knowledge. Sensible 

 phenomena are only names which we ascribe to assumed 

 external manifestations believed to be coordinated with 



