Why do we say that the higher worlds and lower worlds exist? Why can\u2019t there be only this world? Rare it is to come across the Knowledge of the Self. Rarer is to find a teacher established in it. Rarest is to find a Master who is able to explain it to a student and if the student realises it, its a great wonder.
This Truth is not realised by listening to someone who is not established in it. Except listening to a Self-Realised Master, there is no other method says the Upanishad.