ADMINISTRATIVE REPORT LXXXIX 
living in a peculiar environment, and secondarily with the arts 
growing out of the beliefs. Thus the descriptions and discus- 
sions of the accompanying papers cover a great part of the 
range in human activities. 
PRIMITIVE TREPHINING IN PERU 
In every stage of development, knowledge is a resultant of 
preconception and observation; and it is a striking and at first 
sight paradoxical fact that knowledge advances chiefly through 
the weakening and gradual elimination of the preconceptional 
component. It is under this general law that knowledge pro- 
gresses from the remote to the near, from the abnormal to the 
normal, from the ideal to the real; and it follows that, when 
any two stages in the progress of knowledge are compared, 
the earlier is the more heavily burdened with preconception, 
speculation, vague hypothesis, and mysticism. In accordance 
with this law, the barbarian has fewer deductive hypotheses 
and more inductive inferences, relatively to the sum of his 
opinions, than the savage; the civilized man has relatively 
fewer hypotheses than the barbarian; and, in proportion to 
the aggregate of knowledge, scientific men are dominated by 
speculative ideas in a less degree than any other class of man- 
kind. This law of the growth of knowledge is well exem- 
plified in the development of medicine and surgery. Among 
savages, medical practice is little more than divination, sorti- 
lege, or exorcism, performed by the shaman or priest, which 
may chance to benefit the patient or may aggravate the dis- 
order; but gradually the element of experience enters, and 
those modes of treatment which result beneficially tend to 
persist, while those that work injury tend to disappear. As 
experiences accumulate the treatment improves, though the 

irrelevant vagaries of the shamans are long retained; thus 
modes of treatment become established, while the extrava- 
gancies of primitive ideation are gradually forgotten. In this 
way empiric medicine arises; and empiricism in turn gradu- 
ally gives place to scientific medicine, through the elimination 
of meaningless motives coupled with the development of a 
