Would love to get the book for myself...
My opinion:
Thoughts are powerful, they can hurt us or fix us.
when the author said The idea that all suffering is created by thought not by circumstances. I believe the author was trying to tell us that nothing can really hurt us except we think of it as something that can hurt us.
I was watching a podcast one day and the woman said and I quote if I insult you in a language you don't understand, would it hurt you I believe the answer is No because you don't know if I was insulting you or not and probably you haven't thought of it as insult..
So I believe that maybe that's what the author was trying to say although our minds have a way of playing tricks on us.