“I will tell you that there have been no failures in my life. I don't want to sound like some metaphysical queen, but there have been no failures. There have been some tremendous lessons.”

As quoted in Contemporary Artists: A-K (2002) by Sara Pendergast and Tom Pendergast, p. 680
Context: I feel that we are living a very fragmented life; the whole world — you too. So I perceive the world in fragments. It is somewhat like being on a very fast train and getting glimpses of things in strange scales as you pass by. A person can be very, very tiny. And a billboard can make a person very large. You see the corner of a house or you see a bird fly by, and it's all fragmented. Somehow, in painting I try to make some logic out of the world that has been given to me in chaos. I have a very pretentious idea that I want to make life, I want to make sense out of it. The fact that I am doomed to failure — that doesn't deter me in the least.

http://ww.tufts.edu/home/feature/?p=commencement2007&p4=4
Optimism

Мое собственное сердце скрыло бы это от меня, потому что нелюбовь почти как убийство, и я никому не в силах была бы нанести этого удара.
Doctor Zhivago (1957)

James M. McPherson. Tried by War: Abraham Lincoln as Commander in Chief (2008) "Epilogue"
2000s

This has sometimes been paraphrased: "My failures have been errors of judgment, not of intent".
1870s, Eighth State of the Union Address (1876)
Context: I leave comparisons to history, claiming only that I have acted in every instance from a conscientious desire to do what was right, constitutional, within the law, and for the very best interests of the whole people. Failures have been errors of judgment, not of intent.

http://www.usatoday.com/sports/boxing/2005-06-02-tyson-saraceno_x.htm
On himself

Good Enough
Song lyrics, Fumbling Towards Ecstasy (1993)