PHC viu< it\v .\MI i:\-ui.r 1 1<>.\ 



jtient inquiries, .mple, 



during nl 1 r "ii the 



lieat handled throughout In 



.'truinents ly the aid <f which the mind 

 lay hold upon the ultimate p . 



intific progress depends mainly upon two factors 



which incessantly interact tin- >tivngl hening of tin- mind 



-j, and the illumination of phenomena by knowl- 



:;o limit to the insight regarding 



physical processes which this interaction cani -sin it- train. 

 i insight we are enabled to \plon; 



that subsensible world into which all natural plicn- 

 strike their roots, anil from which they derive nutrition. 

 By it '*! to place befoi> i id's eye ; 



itomii: motions which lie far beyond tli >f the 



senseri, and to apply to them reasoning as stringent as that 

 applied by the HUM liani. ian to the : collisions 



isible masses. But once committed to such con -p- 

 tions, there is a risk of being irresistibly led beyond the 

 bounds of inorganic nature. Kven in tl. y stages of 



scientific growth, I found myself more and n Celled 



to re. ryatals, but organic structur* 



f man inclusive, as ca.-es of mole .'ture, 



infinitely more complex, it is true, than those of inot 

 nature, but reducible, in the long run, to the sam- 

 ical laws. In ancient journals I tin 



and speculations relating to these subjects, and attempt, 

 made, by icfcn-nc. -talline phenm 



to p! . image to the mind of tl.- 



in which plants and animals are uuilt up. I 1 may 



be excused for noting a wimple of these early specula; 



issibly known to a few of m\ i.ut which 



a more suitable place than that wh. merly 



ictl. 



in the summer of 1855, with my friend lr. 



ler the shadow of a masi\c elm (,n the bank of 



a ri\ i< of our thoughts and 



conversation was substantially tin-: We regarded the tree 



above us. In opposition to | 



asceii' inches, and budded into innu- 



>le leaves. \\ them t do so a power 



