What I got from this book is that whether Panglos is right or not. Whether Pessimism or Optimism prevailed, it doesn't do any good to philosophy over it.
Man was placed in the garden to work, not to be idle.
I believe that in the end Candide gave up on arguing - he simply realised the pointlessness of doing it and that true happiness will be by living life without thinking about it the whole time.
Thanks for your post.