6 COSMOS. 



inquiry. A Hook of Nature, worthy of its exalted title, can 

 never be accomplished until the physical sciences, notwith- 

 standing their inherent irnperfectibility, shall, by their gradual 

 development and extension, have attained a higher degree -of 

 advancement, and until we shall have gained a more extended 

 knowledge of the two grand divisions of the COSMOS, the 

 external world, as made perceptible to us by the senses; 

 and the inner, reflected intellectual world. 



I think I have here sufficiently indicated the reasons 

 which determined me not to give greater extension to the 

 general picture of nature. It remains for this third and last 

 volume of my Cosmos, to supply much that is wanting in the 

 previous portions of the work, and to present those results 

 of observation on which the present condition of scientific 

 opinion is especially grounded. I shall here follow a similar 

 mode of arrangement to that [previously adopted, for the 

 reasons which I have advanced, in the delineation of nature. 

 But before entering upon the individual facts on which special 

 departments of science are based, I would fain offer a few 

 more general explanatory observations. The unexpected 

 indulgence with which my undertaking has been received by 

 a large portion of the public, both at home and abroad, 

 renders it doubly imperative that I should once more define, 

 as distinctly as possible, the fundamental ideas on which the 

 whole work is based, and say something in regard to those 

 demands which I have not even attempted to satisfy, because, 

 according to my view of empirical *. e., experimental 

 science, they did not admit of being satisfied. These explana- 

 tory observations involuntarily associate themselves with his- 

 torical recollections of the earlier attempts made to discover 

 the one universal idea to which all phenomena, in their causal 

 connection, might be reduced, as to a sole principle. 



The fundamental principle 7 of my work on the COSMOS, as 



7 Cosmos, vol. i. pp. 28-31, and 51-60. 



