Maech 31, 1916] 



SCIENCE 



445 



Science, then, is not infallible and never 

 can be. Equally lacking is the quality of 

 infallibility in scientific truth. The essence 

 of a truth in science lies in its power to ex- 

 plain phenomena in a satisfactory way. If 

 it does not do this, then it is not a truth. 

 In a certain stage of the development of 

 scientific knowledge a theory is found to 

 explain or relate all the known facts in a 

 particular range of phenomena. This is the 

 source of the satisfaction it gives to the 

 scientific mind and at that stage it is ac- 

 cepted as a truth. But subsequently dis- 

 covered facts in the same province may re- 

 fuse to be so explained or related, and the 

 previously accepted truth will, conse- 

 quently, be discarded for one that will give 

 this service. 



An illustration is to be found in the his- 

 tory of the theories of light. Newton held 

 that light emanated from its source in the 

 form of excessively minute particles or cor- 

 puscles, which were supposed to travel with 

 enormous velocity. This "corpuscular" 

 theory in his day and for a hundred years 

 after seemed to explain all the then known 

 phenomena of light. It was not only satis- 

 factory in this respect, but it stimulated 

 further inquiry in the subject. This even- 

 tually led to the promulgation of the "un- 

 dulatory" theory, according to which light 

 is but a wave motion in the cosmic ether. 

 For the last hundred years this has been 

 accepted as a truth, but in its turn it is 

 failing to explain all new facts as they are 

 ascertained, and its acceptance in its orig- 

 inal form as a truth may eventually termi- 

 nate. 



If this is scientific truth, what is there 

 to prevent it from running riot, confusing 

 and misleading rather than guiding? 



The only preventive force is the seien-, 

 tific spirit. It is a development of the qual- 

 ity or tendency of the mind which has com- 

 pelled man in all the periods of his history 



to discard or to recast his truths because 

 they do not work, and to accept new ones 

 because they do work. That tendency in com- 

 mon life has operated crudely and slowly, 

 it has caused countless mistakes and the 

 temporary acceptance of countless errors, 

 but it has brought us to our present stage 

 of civilization. It is indeed nothing else 

 than the pragmatic spirit. The scientific 

 spirit is the pragmatic spirit trained in the 

 strictest fashion to accept only what an- 

 swers rigid tests and reinforced by an in- 

 tense curiosity or desire to know. The very 

 essence of this spirit is manifested in the 

 habit of unceasing, relentless criticism. 

 Without such incessant criticism there 

 would be chaos in science. The scientific 

 spirit, as thus understood, is an all-power- 

 ful factor in establishing scientific truth. 



To some of you, perhaps to many of you, 

 what I have said may appear as a restate- 

 ment of a series of truisms, and I am pre- 

 pared to admit that. I have, however, 

 dwelt on these matters at length because 

 they are of fundamental importance to men 

 of science generally, and, amongst these, to 

 biochemists, especially of the younger gen- 

 eration, who have now to meet an extraor- 

 dinary situation in which these matters are 

 involved. 



A brief sketch of the history of bio- 

 chemistry to the present date will demon- 

 strate what this situation is. 



It would be difficult to say when the his- 

 tory of biochemistiy actually began, for all 

 through the last century a number of con- 

 tributions to chemistry were made which 

 can now be regarded as contributions to 

 biochemistry. The history of biochemistry, 

 however, as a distinct department of knowl- 

 edge, may be said to have begun with 

 Hoppe-Seyler in 1867 in the work from 

 his laboratory, which he subsequently pub- 

 lished under the general title of "Medi- 

 cinische-Chemische Untersuchungen. ' ' The 



