MEMOIR OF GUYOT. 707 



which the law of internal contrasts, as conditions of a more active life, 

 plays so great a part. Hence the whole scheme of that part of earth 

 and man. This law thus became for me the key for the appreciation 

 and understanding and grouping of an immense number of phenomena 

 both in nature and history. My views of the human races and of uni- 

 versal history are, in great part, on the same base. So also the idea of 

 the true sense of the first chapter of Genesis as a characteristic of the 

 great organic epochs." 



His recognition of the same principle in organic nature is expressed 

 as follows in a letter of March 17, 1856, referring in the first paragraph 

 to the view of Agassiz that the sub-kingdoms among animals and the 

 grander divisions among plants represent so many plans of structure: 



" But do we not too much forget that even structure is but a means — 

 the expression of a mode or function of life, which mode or function is 

 the idea of it, and in one sense its cause? If so, then structures only 

 express various aspects and functions of life, animal or vegetable, and 

 they are related and connected together as the various aspects, modes, 

 and functions of organic life are with the essential idea of life itself. 



" Now, life is essentially (I mean phenomenally) growth, develop- 

 ment, movement from phase to phase, from birth to death, and it seems 

 to me that I can find no principle which gives me a more clear, natural, 

 and connected idea of the innumerable types and forms of vegetables 

 and animals than to consider them as typical of so many phases of life, 

 whether of growth, or mode of life, or function of life." 



Guyot endeavored to find the expression of the formula of develop- 

 ment in the details of the systems of life, animal and vegetable, as ex- 

 hibited in the progressive life of the globe as well as the existing 

 species; and the i)receding sentences in his letters were introductory 

 to further explanations with regard to this system. His philosophical 

 ideas were broad and deep enough to embrace the results of all dis- 

 covery, although his illustrations manifested something of the limited 

 knowledge of species and groups of thirty years since. 



In 1862 he delivered a course of lectures at the Smithsonian Institu- 

 tion on this subject, or "The Unity of Plan in the Systems of Life, as 

 exhibited in the Characteristic Ideas and Mutual Relations of the great 

 groups of the Vegetable and Animal Kingdoms:" but, although publi- 

 cation was desired by the Institution and urged by others, the manu- 

 script was never ready. Full stenographic reports were made, which 

 he never found time to revise. 



It is interesting to note, in both Agassiz and Guyot, this full faith in 

 a system of developnient as the best and truest expression of the order 

 of succession in the progress of life, and, in Guyot, the application of the 

 principle to all progress, while, at the same time, neither doubted the 

 constancy of species or the necessity of divine acts for originating spe- 

 cies and carrying forward the development. Agassiz declares, in his 

 " Poissons Fossiles ;" " More than fifteen hundred species of fossil fishes 



