On Genius. 387 
and its strength, if we ascend to the source 
of all our associations, will be derived from 
a more than ordinary acuteness in the original 
susceptibility of pleasure and pain. We may 
state the case in a few words thus. The 
primum mobile of the moral constitution or 
man—the central spring, which puts his fa- 
culties in motion and urges him to action— 
is a discriminating sense of pleasure and pain. 
Upon this primary distinction in our original 
perceptions, are founded all those subsequent 
associations, however remote or extensive, 
which influence our conduct and govern the 
train of our thoughts. The more powerful 
the cause, the stronger the effect: our asso- 
ciations will then be most vivid, when the 
sensations of pleasure and pain connected 
with them, and on which they ultimately 
rest, are most acute. We know what is the 
effect of very strong excitement upon men of 
ordinary talents. When some vivid associ- 
ation has taken possession .of their minds, 
they seem to acquire a force and energy of 
character quite beyond their usual capacity ; 
and, while the excitement lasts, they con- 
ceive, combine and arrange their plans with 
a fertility and promptitude—they act with a 
decision—and speak with a warmth and elo- 
quence—which are the prerogatives of spi- 
