COSMICAL ETHER 39 



those of subtlety and tenuity with the ether, by whose trans- 

 verse vibrations modern physicists have succeeded so happily 

 in explaining, on purely mathematical principles, the pro- 

 pagation of light, with all its properties of double refrac- 

 tion, polarisation, and interference. The natural philosophy 

 of Aristotle further teaches that the ethereal substance 

 penetrates all the living organisms of the earth both plants 

 and animals ; that it becomes in these the principle of vital 

 heat, the very germ of a psychical principle, which, uninflu- 

 enced by the body, stimulates men to independent activity." 

 These visionary opinions draw down ether from the higher 

 regions of space to the terrestrial sphere, and represent it 

 as a highly rarefied substance constantly penetrating through 

 the atmosphere and through solid bodies ; precisely similar 

 to the vibrating light-ether of Huygens, Hooke, and modern 

 physicists. But what especially distinguishes the older Ionic 

 from the modern hypothesis of ether, is the original assump- 

 tion of luminosity, a view, however, not entirely advocated 

 by Aristotle. The upper fire-air of Empedocles is expressly 

 termed 'brightly radiating (Tra/i^ai/oW), and is said to be 

 seen by the inhabitants of the earth in certain phenomena, 

 gleaming brightly through fissures and chasms (xaa/zara) which 

 occur in the firmament. 20 



The numerous investigations that have been made in recent 

 times regarding the intimate relation between light, heat, 

 electricity, and magnetism, render it far from improbable that, 

 as the transverse vibrations of the ether which fills the regions 

 of space give rise to the phenomena of light, the thermal and 

 electro-magnetic phenomena may likewise have their origin 

 in analogous kinds of motion (currents). It is reserved for 

 future ages to make great discoveries in reference to these 



19 See the proofs collected by Biese, op. cit., bd. xi. s. 93. 

 80 Cosmos, vol. i. p 143. 



