READING IS NECESSARY TO RESEARCH. 295 



of several sciences, and he who knows these best is best 

 prepared to explain new results. No natural phenomenon 

 can be fully studied in itself alone, but must also be con- 

 sidered in its relations to many others of different kinds. 

 A knowledge of optics, for example, greatly assists us 

 in understanding the subjects of crystallography, mineral- 

 ogy, cohesion, sound, &c. ; and that of electricity greatly 

 aids us in comprehending magnetism, chemistry, and 

 other sciences. It is evident from this, that extensive and 

 select reading is a valuable preliminary preparation for 

 original scientific research. 



Eeading, however, is only a means towards research. 

 The object is not to amass existing knowledge, but to 

 apply it to facilitate the discovery of more. It is not 

 usually the man who possesses the greatest amount of 

 scientific knowledge who makes the most discoveries. 

 Time occupied in reading and study cannot be employed 

 in experimenting. An excess of reading and study usually 

 also results in the production of an unnecessarily large 

 number of questions and hypotheses, far more than any 

 one man, or even many men, can satisfactorily examine. 



Although a knowledge of science in general, and 

 especially of the particular science involved, is of such 

 great advantage, it is possible for a man who has not been 

 educated in either to acquire the ability to make dis- 

 coveries ; of this Priestley is a notable instance. He was 

 a prolific and rapid discoverer of new and important quali- 

 tative scientific truths. He was entirely self-taught in 

 chemistry, except having attended a course of chemical 

 lectures. He knew but little about substances except the 

 gases, and these were his especial subject, and he is said to 

 have been led to study them in consequence of living near 

 a brewery. His chief researches were commenced when he 

 was about 35 years of age. His experiments were crude ; 



