SCIENTIFIC METHOD 61 



induction have afforded a basis from which deduc- 

 tion has reached far beyond experience. The 

 supreme illustration of the power of combined 

 methods is to be found in Newton's Principia, for 

 here, as Prof. Case has shown in detail, the 

 method is neither the deductive Aristotelian, nor 

 the inductive Baconian, but both; it is the inter- 

 action of induction and deduction in a mixed 

 method. "The full title, Philosophic? Naturalis 

 Principia Mathematica, implies a combination of 

 induction and deduction. It is also a combination 

 of analysis and synthesis: it proceeds from facts 

 to causes as well as from causes to facts." 



THE KEEN EYE. We use this phrase, meta- 

 phorically as well as literally, to describe what 

 may be called a preliminary condition of all 

 scientific investigation one certainly that has led 

 to many discoveries. We mean the observant 

 habit, the alert mind, the appetized intelligence, 

 the inquisitive spirit, which notices whatever is 

 unusual, which sees a problem in the most com- 

 monplace occurrences. It is difficult to define 

 this quality, which is at its highest when sensory 

 alertness is combined with a habit of wondering 

 and pondering. 



Of Clerk Maxwell, who "enriched the inherit- 

 ance left by Newton and consolidated the work 

 of Faraday," it is said that his first recollection 

 was that of lying on the grass before his father's 



