were discontinuous, if between any two beings an intermediate type were logically capable of existing, but actually non-existent, the universe 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 continuity owed its vogue in part, also, to the influence of the Leibnitian calculus, which had brought infinitesimals and the notion of the continuum 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:
- Günther, "Die Wissenschaft vom Menschen im 18ten Jahrhundert," p. 30.