There is always time for failure.
John Mortimer
Failure is the condiment that gives success its flavor.
Truman Capote
Success is more dangerous than failure, the ripples break over a wider coastline.
Graham Greene
The theory seems to be that as long as a man is a failure he is one of God's children, but that as soon as he succeeds he is taken over by the devil.
H. L. Mencken