2 $4 /Tir// on the Ufe of Symbols. 
difirance from the fun, and returns quickly, 
if engaged in the immediate execution of his 
commands, might lead the firft aftronomers to 
fuppofe, that this planet was facred to the Deity, 
whom their mythology had made the fervant, 
officer or meffenger of the Gods; and, therefore, 
as its fymbol, they chofe the Caduceus the ftaff of 
office, which that Deity was fuppofed to bear, 
(fee fig. 5. in the plate.) 
If this attempt, to explain the origin of thefe 
fymbols, be admitted as plaufible, the credit 
of their invention, and their firft application 
mult be afcribed to aftronomy. But a greater 
difficulty now arifes, to point out, by what 
principles the chemifts were led to appropriate 
them to their art ; an undertaking much more 
perplexed, and, which my attempts to illuftrate, 
will require all the indulgence and favour of 
this learned Society. I give up entirely their 
pretenfions to the invention of thefe characters, 
and, therefore, ffiall not pay any attention here 
to the attempts, which Boerhaave and others have 
made to explain them; but ffiall proceed upon 
a quite different plan. 
The peculiar fplendour of the fun and moon 
had without doubt been long noticed; and long 
before the introduction of chemical fcience, the 
language of poetry (and in the earlieft ages al- 
moft all language was poetical, that is, figurative) 
had difcriminated that of the former by epithets, 
borrowed 
