The Fu T‘ien; metaphorical. The folly of pursuing objects beyond one's strength.

1The weeds will but the ranker grow,
  If fields too large you seek to till.
To try to gain men far away
  With grief your toiling heart will fill.

2If fields too large you seek to till,
  The weeds will only rise more strong.
To try to gain men far away
  Will but your heart's distress prolong.

3Things grow the best when to themselves
  Left, and to nature's vigor rare.
How young and tender is the child,
  With his twin tufts of falling hair!
But when you him erelong behold,
  That child shall cap of manhood wear!