OF THE COSMOS. INTRODUCTION. 13 



essence of things may be known by ratios of numbers, and 

 their alterations and transformations by combinations of 

 numbers. Plato's Physics also contain attempts to reduce 

 all the essences of substances in the universe, and their 

 gradations of changes, to corporeal forms ; and these to the 

 simplest (triangular) plane figures. ( 14 ) But what the ulti- 

 mate principles (as it were the elements of the elements), may 

 be, "this," said Plato, with modest diffidence, "is known to 

 God alone, and to whomso is beloved by Him among men." 

 This mathematical treatment of physical phenomena, the 

 formation of atomic doctrines, the philosophy of measure 

 and of harmony, have continued to a late period to influ- 

 ence the development of the natural sciences : they have 

 also contributed to lead fanciful discoverers astray from the 

 true road, into by-paths which it may be requisite to notice 

 in the history of the physical contemplation of the Universe. 

 " There dwells a peculiar and fascinating charm recognised 

 by all antiquity in the simple relations of time and space 

 as manifested in tones, numbers, and lines."" ( 15 ) 



The idea of the order and government of the Universe shines 

 forth pure and exalted in the writings of Aristotle. All the 

 phenomena of Nature are described in the "Auscultationes 

 Physicse" as moving vital activities of a Universal Power. 

 On the " unmoved Motor of the World depend Heaven and 

 Nature," ( 16 ) Nature being the terrestrial sphere of phse- 

 nomena. The " Orderer," and the final cause of all alte- 

 rations which can be perceived, must be regarded as imper- 

 ceptible to sense, as distinct from all matter. ( 17 ) Unity 

 in the different manifestations of force in substances is raised 

 by Aristotle to the rank of a leading principle, and these 

 manifestations of force are themselves always reduced to 



