Microbiology Takes the Stage 205 



vance any idea which cannot be proven in a simple and 

 decisive manner. Cultivate the critical spirit. In itself, it 

 is neither a provoker of ideas nor a stimulant to great 

 things. It always has the last word, however." 



There has been much elaboration on Pasteur's dictum, 

 "Chance comes only to the prepared mind," or as Nicolle 

 expressed it, "Chance favors only those who know how to 

 court her." Helmholtz said, "Happy ideas come unex- 

 pectedly without effort, like an inspiration. So far as I was 

 concerned, they have never come to me when my mind was 

 fatigued, or when I was at my working table. . . . They 

 came particularly readily during the slow ascent of wooded 

 hills on a sunny day." The poet Byron expressed it in 

 somewhat different terms: "To be perfectly original one 

 should think much and read little, and this is impossible, 

 for one must have read before one has learnt to think." 

 Theobald Smith emphasized that "Discovery should come 

 as an adventure rather than as the result of a logical process 

 of thought." 



The ability of the investigator to discriminate is another 

 aspect of the methods of discovery that has often been neg- 

 lected. It may not be so spectacular as chance but is more 

 certain to bear fruit. This was well expressed by Hans 

 Zinsser: "The scientist takes off from the manifold observa- 

 tions of predecessors, and shows his intelligence, if any, 

 by his ability to discriminate between the important and 

 the negligible, by selecting here and there the significant 

 stepping-stones that will lead across the difficulties to new 

 understanding. The one who places the last stone and 

 steps across to the terra firma of accomplished discovery 

 gets all the credit. Only the initiated know and honor those 

 whose patient integrity and devotion to exact observation 

 have made the last step possible." Paul Ehrlich emphasized 

 the need for "much testing, accuracy and precision in ex- 

 periment, and no guess work or self-deception." 



To envisage the progress of science, we may again refer 



