I believe that this quote is saying that only our true self, our soul, is our truth. The truth inside will always be there us, until we die that is our reference point. Therefore, making our soul the "whole world".
All except 3 & Better than "Learn from the mistakes of others." Better than "There is no 'We'. you (individually) have NOTHING to do with their success or failure" Solid advice - I love this. (Hate the typos, though.
✨ no matter how dark times of your life may be, you have the power within you to shine bright & light up the darkness of any night. surround yourself with positivity & watch your life illuminate greatly.