Walls

Sometimes you put walls up not to keep people out, but to see who cares enough to break them down.

Luck

Shallow men believe in luck.
Strong men believe in cause and effect (R.W. Emerson)

Youth

Youth is a circumstance you can't do anything about.
The trick is to grow up, without getting old.../F.L. Wright

Horizon

We all live under the same sky, but we don't all have the same horizon/K. Adenauer.