CREATIVE SCIENCE 335 



of a vital detail later observed by Pasteur. Lalande, thoroughly com- 

 petent astronomer, plots the position of the stars. Two observations of 

 the same star fail to agree. To us, knowing of the existence of Nep- 

 tune, the discrepancy indicates a phenomenon. To Lalande it indi- 

 cated only an observational error, and he threw away the opportunity 

 to discover a new planet. Rayleigh published a note calling attention 

 to a small but puzzling disagreement he had observed in the densi- 

 ties of gaseous nitrogen. Not one of the hundreds of scientists who 

 read the report of this celebrated physicist saw in it anything but a 

 trivial discrepancy. Hillebrand, meticulous analytical chemist, ob- 

 served the spectrum of "nitrogen" extracted from clevite, and noted 

 certain lines he was unable to associate with those of any element 

 known to him. He dismissed the strange lines as some peculiar arti- 

 fact of the conditions under which the discharge was excited. 



Apparently it is all too easy to see not a phenomenon but, with 

 Mitscherlich, nothing at all; with Lalande, an observational error; 

 with Rayleigh's contemporaries, a trivial discrepancy; or with Hille- 

 brand, an artifact of the apparatus. By such expedients the unex- 

 pected manifestation is, if at all recognized, dismissed not as a phe- 

 nomenon but as an irritation. Accidental discoveries which are focal 

 discoveries can be missed, have been missed, by scientists of high 

 competence. And we cannot simply say that those who did not miss 

 them are a "lucky" few of many whom history might equally have 

 made heroes. The "luck" is too unevenly distributed: the vast ma- 

 jority of scientists have none, while "happy accidents" seem con- 

 stantly the fortune of such as Priestley, Faraday, and Bernard. 

 Whence derives their serendipity? 



THE THRESHOLD OF IMPRESSIONABILITY 



I read a book that interests me. All around me are sources of sounds 

 that set my eardrums into a haze of vibrations. But most of these 

 auditory stimuli are dismissed without ever rising to full aware- 

 ness— e.g., the children bouncing a ball, the dog scratching at the 

 door, my neighbor mowing his lawn. In order to "pay attention" to 

 those few (among many) sensory stimuli that matter, I have de- 

 pended on an automatic screening mechanism that excludes from 

 consciousness myriad "distractions." Even within the focus of my at- 

 tention I will have failed to notice some things, e.g., most misprints 

 or editorial inconsistencies. 



