_ PHYSICAL anv LITERARY. 13 
light can move thro’ light in all imagi- 
nable direCtions, without occafioning the 
leaft perceivable confufion or deviation 
- from its reétilinear courfe. Many have 
been induced, from this confideration, to 
believe it incorporeal; and all who have 
thoroughly ‘weighed the difficulty, have 
feen the neceflity of afcribing a fubtility to 
itincomparably greater than weare led, by 
any phenomena, to afcribe to any other {pe- 
cies of bodies in nature. There is no phy- 
fical point in the vifible horizon which 
does not fend rays to every other point; 
no {tar in the heaven which does not fend 
rays to every other ftar: The whole hori- 
zon is filled with a fphere of rays from 
every point.in it; and the whole vifible 
univerfe, with a {phere of rays from eve- 
ry ftar. | In fhort, for any thing we know, 
there are rays of light joining every two 
phyfical points in the univerfe, and that 
in contrary dire€tions; except where o- 
paque bodies interveen. 
2. THOsE who fuppofe that light is 
nothing elfethan vibrations or pulfes pro-~ 
_ pagated through a fubtile elaftic medium - 
from 
