Brutes find out where their talents lie:
a bear will not attempt to fly. 
A founder'd horse will oft debate,
Before he tries a five-barr'd gate;
a dog by instinct turns aside,
Who sees the ditch too deep and wide;
But men we find the only creature
Who, led by folly, combats nature;
Who when she loudly cries -- forbear,
With obstinacy fixes there; 
and, where his genius least inclines, 
Absurdly bends his whole design. 
Jonathan Swift