938 PHILOSOPHY OF ZOOLOGY. 
is difficult to pomt out the principles by which we would be 
guided, unless the golden rule be considered as one of the 
natural standards of duty,—‘ All things whatsoever ye 
would that men should do to you, do ye even so to them.” 
To ascertain our duty would be an easy task, were the 
mind always to pursue so straight a course. But we often 
act in direct opposition to those rules of conduct which we 
have previously established. Experience tells us, that the 
conduct of others is equally consistent as our own. By 
persevering in this perverted course, we destroy that stand- 
ard which our own experience had erected, and act upon 
another which we would formerly have considered imper- 
fect and foolish. By habit or custom, our notions of duty 
are thus changed, converting, with respect to our conduct, 
evil into good, and good into evil. 
Duty, according to the precedmg remarks, consists in 
employing the most efficacious means to secure the greatest 
quantity of enjoyment, and to avoid every degree of pain. 
That the discovery of duty is an intellectual process, is ob- 
vious from the variety of opinions which have been enter- 
tained on the subject ; the variable influence which these 
opinions exercise over the will; and the effort required to 
comply with them. 
When a standard or rule of duty is proposed to us, we 
judge from experience, testimony, and analogy, of its suita- 
bleness, —and if embraced, we ever after condemn any con- 
duct which is in opposition to it, (although we commit it,) 
and continue to do so, until a more perfect standard has 
been proposed and received. 
By the help of memory, we acquire an astonishing quick- 
ness of perceiving whether we act conformably or opposite- 
ly to this received standard. We feel pleasure in the one 
case, and pain in the other; both of which are encreased 
according to our notions of the value of the standard by 
which we try ourselves. 'To the operations of the memory 
