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SCIENCE 



[N. S. Vol. XLV. No. 1167 



world which was held by the early Hebrews 

 and which appears to us so fantastic, was, 

 after all, based upon facts, but like many 

 theories which have followed it, upon too 

 small a body of fact to supply a firm foun- 

 dation. 



It has often been said that the theories so 

 tenaciously held by one generation are 

 abandoned by the next. To a large extent 

 this has been true of the past, and the ex- 

 planation is in part that scientists are not 

 less fallible than others, but are subject to 

 like limitations in prejudice, in undue rev- 

 erence for authority, in regard for the sci- 

 ence vogue of their time, and in many other 

 conditions. To an even greater degree the 

 overturning of scientific doctrines has been 

 due to the failure of both the scientists and 

 their critics to distinguish clearly between 

 legitimate theory within those fields where 

 views may be rigidly tested, and audacious 

 conjectures which have been offered under 

 the verisimilitude of facts to explain prob- 

 lems whose complete solution belongs to the 

 remote future, if they may not be regarded 

 as insoluble by any methods which have yet 

 been discovered. 



The process of eruption within a volcanic 

 vent as regards its physical and chemical 

 aspects offers a problem which, though by 

 no means simple, may yet be subjected to 

 observation and experimentation and 

 doubtless belongs to the realm of soluble 

 scientific problems. The materials present 

 at the earth 's center and their peculiar state 

 of aggregation, are by contrast very largely 

 a subject of conjecture, and attempts to 

 class these problems together lead to inex- 

 cusable confusion. 



A theory has been defined as an expla- 

 nation founded upon inferences drawn 

 from principles which are established by 

 evidence. By contrast the hypothesis is a 

 supposition as yet untested. The working 

 hypothesis of the scientist occupies an in- 

 termediate position and aims to explain, at 



least in part and better than any other, a 

 set of related phenomena which are already 

 known, and it is considered to be in a pro- 

 bationary stage until confirmed through 

 rigid tests the nature of which is suggested 

 by the hypothesis itself. When so examined 

 it may be found wanting; but, if well 

 founded, experimentation is likely to result 

 in its improvement by pruning of error 

 quite as much as through enlargement of 

 the body of truth which it contains. 



The inheritance of knowledge by the an- 

 cients was, compared to ours, small indeed ; 

 and with their limited resources in mate- 

 rials and in methods of investigation, even 

 more than we, they saw "through a glass 

 darkly. ' ' It was therefore but natural that 

 the theories which they evolved should have 

 been largely the product of introspective 

 reasoning. In consequence it was in the 

 field of mathematics that they achieved 

 their greatest triumphs, and as an inheri- 

 tance a mathematical language was common 

 to other fields of science even late in the 

 seventeenth century. Viewing the marvels 

 of the universe with their limited outfit of 

 exact knowledge, the ancient philosophers 

 invoked the supernatural and the mysteri- 

 ous to explain whatever was baffiing and 

 otherwise incomprehensible. Without books 

 the dissemination of knowledge was limited 

 to the narrowest channels and was accom- 

 plished by the disciples of each leader of 

 thought, who was thus under the tempta- 

 tion of finding an answer to all questions 

 and founding an individual school of phi- 

 losophy. 



With the invasions of the barbarian Huns 

 and the Germanic tribes in the fifth cen- 

 tury of the Christian era, there ensued the 

 eclipse of civilization which we are accus- 

 tomed to refer to as the ' ' Dark Ages. ' ' Out 

 of the darkness of these centuries of in- 

 tellectual stagnation we catch a glimpse 

 which indicates that individual minds were 

 still active in their search for the truth. 



