468 THE POPULAR SCIENCE MONTHLY 



were discontinuous, if between any two beings an intermediate type 

 were logically capable of existing, but actually non-existent, the uni- 

 verse would stand convicted of irrationality. A thing for the existence 

 of which there was just as much "reason" as there was for the existence 

 of certain other things would have failed of realization, while the others 

 arbitrarily enjoyed the privilege of actuality. The principle of con- 

 tinuity owed its vogue in part, also, to the influence of the Leibnitian 

 calculus, which had brought infinitesimals and the notion of the con- 

 tinuum peculiarly into fashion. 



Applied primarily to the " monads " of Leibniz's metaphysics, the 

 principle found a multitude of other applications. It served, for 

 example, as the chief basis of the arguments for optimism of which 

 the early eighteenth century was so fond. Pope's " Essay on Man " 

 is full of the argument from the necessity of continuity to the necessity 

 of imperfections and apparent evils. 



Vast chain of being! which from God began; 



Nature's ethereal, human, angel, man, 



Beast, bird, fish, insect, whom no eye can see, 



No glass can reach; from infinite to thee, 



From thee to nothing. On superior powers 



Were we to press, inferior might on ours; 



Or in the full creation leave a void, 



Where, one step broken, the great scale 's destroyed. 



For the limitations of man's lot the sufficient consolation is that 

 the principle of continuity requires them ; in a system 



Where all must full or not coherent be, 

 And all that rises, rise in due degree, — 

 Then in the scale of reasoning life 'tis plain 

 There must be, somewhere, such a rank as man. 



From the assumption of the same principle sprang the inquiries from 

 which the science of anthropology may be said eventually to have 

 originated. As a historian of the beginnings of that science has said: 

 The question concerning the line of demarcation between man and the 

 animal kingdom was plainly forced upon anthropology by the philosophy of 

 Leibniz. The lex continui demanded the discovery of that "grade" (nuance) 

 of existence among the higher organisms which comes nearest to the human 

 species. And so there began the celebrated quest of the ' ' missing link. ' ' In 

 the first phase of this quest, the missing link was sought at the lower limits of 

 humanity itself. It was held to be not impossible that among some of the 

 more remote peoples semi-human beings might be found, such as had now and 

 then been described in travelers' tales. Some voyagers had testified to having 

 seen with their own eyes men with tails; others had encountered tribes incapable 

 of speech. Linnaeus mentions a homo troglodytes concerning whom it was not 

 established with certainty whether he was more nearly related to the pygmies or 

 to the orang-outang. The most eminent men of science down to a late period in 

 the eighteenth century hesitated to reject absolutely the possibility of the exist- 

 ence of such beings. 9 



8 Giinther, "Die Wissenschaft vom Menschen im 18ten Jahrhundert, " p. 30. 



