466 COSMOS. 



HISTORY OF THE PHYSICAL CONTEMPLATION OF THE 

 UNIVERSE. PRINCIPAL CAUSES OF THE GRADUAL DEVE- 

 LOPMENT AND EXTENSION OF THE IDEA OF THE COSMOS 

 AS A NATURAL UNITY. 



THE history of the physical contemplation of the universe is 

 the history of the recognition of the unity of nature, the repre- 

 sentation of the efforts made by man to comprehend the 

 combined action of natural forces on the earth and in the 

 regions of space; and hence it designates the epochs of ' 

 advancement in the generalisation of views ; being a portion of 

 the history of our world of thought, in as far as it refers to 

 objects manifested by the senses, to the form of conglomerated 

 matter and the forces inherent in it. 



In the section of the first portion of this work, relating to 

 the limitation and scientific treatment of a physical description 

 of the universe, I' hope I may have succeeded in developing 

 with clearness the relation existing between the separate 

 natural sciences and the description of the universe, (the 

 science of the Cosmos,) and the manner in which this science 

 simply draws from these various branches of study the mate- 

 rials for its scientific foundation. The history of the know- 

 ledge of the universe, of which I here ipresent the leading 

 ideas, and which, for the sake of brevity, I name, either simply 

 the history of the Cosmos, or the history of the physical con- 

 templation of the universe, must not, therefore, be confounded 

 with the history of the natural sciences, as given in many 

 of our leading elementary works on physics and physiology, 

 or on the morphology of plants and animals. 



In order to give some idea of what has been collected at 

 separate epochs, under this point of view, it appears most 

 desirable to adduce separate instances illustrative of the sub- 

 jects which must either be treated of or discarded in the 

 succeeding portions of this work. The discoveries of the 

 compound microscope, of the telescope, and of coloured polari- 

 sation, belong to the history of the Cosmos, since they have 

 afforded the means of discovering that which is common to 

 all organisms ; of penetrating into the remotest regions of space ; 

 of distinguishing between reflected or borrowed light, and the 



