THE PROGRESS OF PSYCHOLOGY. 781 



lives. Inert matter may be observed and measured more readily 

 than the living body ; physics consequently preceded biology in 

 its development. The changes of mental life are more fleeting 

 and obscure than those of the body. It is natural, therefore, 

 that, as biology is more backward than physics, so psychology 

 should be more backward than biology. There was a time when 

 all the sciences were nourished by philosophy. In Greece the 

 philosopher and the man of science were identical, and those who 

 most advanced mathematics and science in the revival of learn- 

 ing are called philosophers. With the increase of knowledge 

 division of labor became necessary, and the separate sciences 

 were defined. Those sciences were first developed which found 

 data ready in the common knowledge of daily life, and which 

 embraced subjects where experiment and measurement could be 

 most readily used. The close relation in which psychology still 

 stands to philosophy is thus explained by its comparative back- 

 wardness. This relation is not essentially different from that of 

 the other sciences. Philosophy is not the arithmetical sum of the 

 special sciences, but has a peculiar task. It seeks to investigate 

 the conditions of knowledge, and to form a theory of the ultimate 

 nature and meaning of things. Psychology is no more concerned 

 with these matters than is physics. Experimental and mathe- 

 matical physics need not and should not investigate the origin and 

 ultimate nature of matter, nor should psychology as a natural sci- 

 ence concern itself with the origin, destiny, and meaning of mind. 

 The subject-matter of psychology corresponds exactly to that 

 of any other natural science. As physiology studies the phe- 

 nomena of the living body, so psychology studies the phenomena 

 of mind. It is often urged as an objection to psychology that 

 the student can observe one mind only, but it is equally true that 

 the student of physics can observe with one mind only. Were 

 mental processes so irregular and idiosyncratic as is sometimes 

 assumed, there would be no science of psychology, but physics 

 would be equally out of the question. Psychology is not con- 

 cerned with individual peculiarities, but with the laws to which 

 all mental processes are subject. Its position is similar to that 

 of physiology, which studies individual organisms in order to 

 learn general truths concerning nutrition, movement, etc. The 

 problems of psychology are evidently complicated by the fact 

 that individual minds differ. But this difference is largely a 

 matter of comparatively unimportant detail. The position of 

 psychology is not very different from that of other sciences. 

 Should astronomy seek to determine the orbits of all the satellites, 

 of all the planets, of all the suns in the universe, it would have a 

 hopeless task ; but, if we understand one solar system, we have 

 an astronomy to a large extent universal. 



