Adwaita Vedanta: As real as the dreamer considers himself or herself to be, so real does the dream world seem to be. If you are real, the world is real, then Adwaita says God is also real. But this waker and the wacker's world are none other than pure consciousness. It's not a separate real God out there. Others don't exist. I alone exist.
Swami Sarvapriyananda teaches one of the shortest and most profound upanishads accompanied by Gaudapada's Karika. This lecture covers Mantra 5-6.