What was said previously by Churchill is understood today by many of us and I personally agree with his opinion because this is the basis of a social living life, meaning that in living our life we fail and succeed and this is the basis of our experience and our development. The same applies in literature, fiction, or non fiction there is always failure and success. For example in the work of
The lost Honour of Katharina Blum by Heinrich Bolle when Katharina Blum is accused of being a whore, communist and an atheist her life still continues and still she fights for her innocence and struggles through the process. Therefore it is true to say that "Failure is not fatal" and "success is not final".
However, in Making History by Brian Friel Hugh O'Neill gives up his position and leaves his country and pride because he had lost the battle of Kinsale. Therefore, in this case the statement by Churchill does not seem to be truly true.