570 COSMOS 



ceased to be associated with separate and locally defined poli- 

 tical occurrences. Great inventions now first emanated from 

 spontaneous intellectual power ; and were no longer solely 

 excited by the influence of separate, external causes. The 

 human mind, acting simultaneously in several directions, 

 created, by new combinations of thought, new organs, by which 

 the human eye could alike scrutinise the remote regions of 

 space and the delicate tissues of animal and vegetable structures 

 which serve as the very substratum of life. Thus the whole of 

 the seventeenth century, whose commencement was brilliantly 

 signalised by the great discovery of the telescope, together 

 with the immediate results by which it was attended from 

 Galileo's observation of Jupiter's Satellites, of the crescentic 

 form of the disc of Venus, and the spots on the sun, to the 

 theory of gravitation discovered by Newton ranks as the 

 most important epoch of a newly- created physical astronomy. 

 This period constitutes, therefore, from the unity of the 

 eiforts made towards the observation of the heavenly bodies, 

 and in mathematical investigations, a sharply-defined section 

 in the great process of intellectual development, which, since 

 then, has been characterised by an uninterrupted progress. 



In more recent times, the difficulty of signalising separate mo- 

 menta increases in proportion as human activity becomes more 

 variously directed, and as the new order of social and political 

 relations binds all the various branches of science in one 

 closer bond of union. In some few sciences, whose develop- 

 ment has been considered in the history of the physical con- 

 templation of the universe, as, for instance, in chemistry and 

 descriptive botany, individual periods may be instanced, even 

 in the most recent time, in which great advancement has been 

 rapidly made, or new views suddenly opened, but, in the his- 

 tory of the contemplation of the universe, which, from its 

 very nature, must be limited to the consideration of those 

 facts regarding separate branches of science, which most 

 directly relate to the extension of the idea of thej^osmos con- 

 sidered as one natural whole, the connection of definite 

 epochs becomes impracticable, since that which we have 

 named the process of intellectual development pre-supposes 

 an uninterrupted simultaneous advance in all spheres of Cos- 

 mical knowledge. At this important point of separation 

 between the downfall of the universal dominion of the Romans 



