32 CONSISTENCY OF GEOLOGICAL 
It appears highly probable from recent disco- 
veries,* that light is not a material substance, but 
only an effect of undulations of ether ; that this 
infinitely subtle and elastic ether pervades all 
space, and even the interior of all bodies ; so 
long as it remains at rest, there is total dark- 
ness ; when it is put into a peculiar state of 
vibration, the sensation of light is produced : 
this vibration may be excited by various causes ; 
e. g. by the sun, by the stars, by electricity, com- 
bustion, &c. If then light be not a substance, 
but only a series of vibrations of ether, i. e. 
an effect produced on a subtle fluid, by the 
excitement of one or many extraneous causes, it 
can hardly be said, nor is it said, in Gen. i. 3, to 
have been created,-^ though it may be literally 
said to be called into action. 
Lastly, in the reference made in the Fourth 
Commandment, Exod. xx. 11, to the six days of 
the Mosaic creation, the word asah, ''made," is 
the same which is used in Gen. i. 7, and Gen. i. 
16, and which has been shown to be less strong 
and less comprehensive than hara, ''created;" 
and as it by no means necessarily implies crea- 
tion out of nothing, it may be here employed 
* For a general statement of the unclulatory theory of light, 
see Sir John Herschell, art. Light, part iii. sec. 2. Encyc. 
Metropol. See also Professor Airy's Mathematical Tracts, 2nd 
edit. 1831, p. 249; and Mrs. Somerville's Connection of the 
Physical Sciences, 1834, p. 185. 
t See Note, p. 26. 
