RELATIONS TO OTHER SCIENCES 419 



medicine and public health. The separate statistical studies of school- 

 children's eyes are now numbered by hundreds or thousands. Some 

 are of much higher value than others. But taken together, they 

 afford a broad and substantial basis for the conclusions: that as 

 schools are now conducted throughout the civilized world, school- 

 life taxes the eye to near its full capacity for active work; that un- 

 favorable influences, like insufficient light, uncorrected ametropia, 

 or impaired general health, render the strain of school-life disastrous, 

 and cause the eye to be permanently damaged. That merely the 

 normal requirements of the body during a stage of rapid develop- 

 ment may cause break-down under ordinary school-work, with com- 

 paratively favorable conditions; and that when working to near 

 full capacity, individual needs and peculiarities must be taken care- 

 fully into account. The enormous aggregate of disability and suffer- 

 ing, brought about by disregard of these conditions of maximum 

 effective work, make these studies of the eye under school-life very 

 important to those who labor in the field of preventive medicine. 



These studies of the eyes of school-children also have for those 

 who study abnormal psychology the suggestive value of very definite 

 and accurate observations in a related field. It is chiefly because of 

 the analogies of eye-strain and brain-strain that we cannot admit 

 extravagant claims for the influence of the former in causing all the 

 ills that the nervous system can manifest. If correction of errors of 

 refraction will not prevent all sorts of neuroses and psychoses, the 

 study of eye-strain and its prevention will throw as much light upon 

 the nature and prevention of brain-fag and nerve-strain as any line 

 of study open to the worker for the prevention of such conditions, 

 be he neurologist, teacher, or social reformer. 



In another and quite different direction the straight course of the 

 ophthalmologist, working at his daily routine, carries him into the 

 domain of public health. The group of contagious inflammations of 

 the conjunctiva, especially the still indefinite condition called tra- 

 choma, are of enormous importance for their bearing upon public 

 health. Social customs, the regulation of immigration, and the eco- 

 nomic and educational problems raised by blindness, are all inti- 

 mately interwoven with the recognition and treatment of these 

 diseases. 



Training of the Worker. Finally, an essential relation of each 

 department of science to other departments is the educational 

 relation. This vast accumulation of observed fact and analogy, of 

 connected cause and effect; this mighty web of interweaving general- 

 ization, which our Congress of Arts and Science attempts imper- 

 fectly to reflect, this huge phenomena of modern science, is of 

 value chiefly as it becomes possible to transmit it from generation to 

 generation. It is the application of knowledge to the needs of men, 



