HEREDITY IN PHYSIOLOGY, IN MEDICINE, 

 AND IN PSYCHOLOGY. 



THERE are many grounds of pride and satisfaction for 

 the mind in the sciences known to man, but reasons for hu- 

 mility and bitter regret are also supplied by them to the 

 full. Spite of the persistent strivings and labored medita- 

 tions of the legions of investigators who have gone before 

 us, Nature still has her deep and dark abysses, at whose 

 blank look all insight turns to blindness, all boldness dies 

 in fear, and all confidence becomes despair. When we at- 

 tempt to throw a little light upon the heart of these mys- 

 terious chasms, that light merely reflects to our view the 

 ghosts of our own ignorance, and we gain from the futile 

 effort only a fresh conviction of our own impotence and 

 poverty. It would be wise to gain from it something 

 more ; I mean, a lesson to benefit us. Indeed, nothing 

 should so chide us back to humility and patience, so cool 

 our presuming eagerness and daunt our daring arrogance, 

 as the study of those phenomena which Providence seems 

 to have ordained purposely to baffle human inquisitiveness. 

 Yet many men affect to be unconscious of the astounding 

 and intricate operations which are taking place in regions 

 that sight and sense never sound, and stubbornly dispute 

 the existence of unseen activities and unfelt powers. This 

 is the deadly, doubting temper that the evidence of those 

 sphinxes of which we are now treating must be brought 

 to attack. The lesson is all the more eloquent because, by 

 strange contrast, those questions that defy every kind of 



