NO MAN really knows enough
To be hateful to his brother,
None is rich enough to cuff
And be cruel to another;
None so clever that he can
Justly wrong his fellow man.

No one is so strong that he
Has the right to curb the weak,
None so great that properly
He can trample down the meek;
There is nothing in success
That excuses selfishness.

Climb unto the topmost bights,
Win yourself an honored name,
But respect another's rights,
Raise the weak and help the lame;
Strength of muscle or of mind
Gives no right to be unkind.

Edgar Albert Guest

http://www.poemhunter.com/poem/the-limitations-of-greatness/