MCGEE 



and vegetal species ; later it was extended (first intuitively and 

 then purposively) to other realms of nature, and was found 

 equally applicable to species of the sub-organic realm, such as 

 minerals and mountains, and to those of the super-organic realm, 

 such as knives and nations — when it became evident that the 

 principle involves involution as well as that evolution so con- 

 spicuous in the organic world. With this extension the doctrine 

 becomes The Develo-pment of Sfecies^ and this phrase expresses 

 the third cardinal principle of Science — the gift of biology, 

 i. e.y of phytology and zoology jointly. 



Naturally the promulgation of three revolutionary doctrines 

 within a century (1760-1860) produced an intellectual surfeit. 

 The principle of indestructibility had lain germinant for two 

 millenniums, and so found men's minds ready for the final plant- 

 ing ; even the principle of persistence met a need of thought, 

 and encountered little opposition ; but the principle of develop- 

 ment found most mental fields already stocked with long-set 

 growths and little prepared for the latest seeding. A conse- 

 quence of the indifference or antipathy of the average mind 

 was voluminous discussion, with the spontaneous separation of 

 thinkers into opposing schools ; and in due course Science be- 

 came a cult, and Thomas H. Huxley its most vigorous expo- 

 nent. As the discussion proceeded, the principle of development 

 was rounded out and applied to new problems ; and as the ap- 

 plications multiplied, it was found to present many analogies 

 with the principles of indestructibility and persistence. Mean- 

 time a science of the earth was rapidly crystallizing about Sir 

 Charles Lyell's idea of uniform process in earth-building — the 

 ' uniformitarianism ' of that day of redundant doctrines — while 

 under the masterly interpretation of Huxley and others, paleon- 

 tology was resurrecting the record of early life on the earth ; 

 and the several movements eventually joined in the formulation 

 of a fourth principle, complementary to those of earlier decades 

 and so harmonious with them as to facilitate the apprehension 

 and adoption of the entire series. This fourth principle has 

 ever smce been regarded as a (if not the) cardinal principle of 

 science ; in Huxley's happy phrase it is The Uniformity of 

 Nature. The principle must be credited largely to Geology 



