The enlightened person sees, if I am the awareness, in me alone all of this is appearing. So that guy, all those people in the world, they are none other than me. Their suffering is my suffering. It comes from oneness, it does not come from difference. When we would say, I want to go back to the dream to have pizza,. it's something like pizza, it's something different from me, it's really there. That's ignorance.
Swami Sarvapriyananda teaches one of the shortest and most profound upanishads accompanied by Gaudapada's Karika. This lecture covers Mantra 7 (Part 2).