The scientific study of man is the most difficult of all branches of knowledge. It requires, in the first place, an entire new terminology to get rid of that enormous load of prejudices with which every term applied to the malformations, the functional disturbances, and the organic diseases of the moral nature is at present burdened. Take that one word Sin, for instance: all those who have studied the subject from nature and not from books know perfectly well that a certain fraction of what is so called is nothing more or less than a symptom of hysteria; that another fraction is the index of a limited degree of insanity; that still another is the result of a congenital tendency which removes the act we sit in judgment upon from the sphere of self-determination, if not entirely, at least to such an extent that the subject of the tendency cannot be judged by any normal standard.
To study nature without fear is possible, but without reproach, impossible. The man who worships in the temple of knowledge must carry his arms with him as our Puritan fathers had to do when they gathered in their first rude meeting-houses. It is a fearful thing to meddle with the ark which holds the mysteries of creation. I remember that when I was a child the tradition was whispered round among us little folks that if we tried to count the stars we should drop down dead. Nevertheless, the stars have been counted and the astronomer has survived. This nursery legend is the child's version of those superstitions which would have strangled in their cradles the young sciences now adolescent and able to take care of themselves, and which, no longer daring to attack these, are watching with hostile aspect the rapid growth of the comparatively new science of man.
The real difficulty of the student of nature at this time is to reconcile absolute freedom and perfect fearlessness with that respect for the past, that reverence, for the spirit of reverence wherever we find it, that tenderness for the weakest fibres by which the hearts of our fellow-creatures hold to their religious convictions, which will make the transition from old belief to a larger light and liberty an interstitial change and not a violent mutilation.