Dream is the projection of the mind. Everything of the dream enjoys the same degree of reality. Yet some persion, thing or transaction of the dream has the special power to wake us up.
The seventh chapter of the Chandogya Upanishad, which is a dialogue between the great sage Sanatkumara and his younger brother, turned disciple, the famous Narada, makes us realise that all knowledge is the play of words alone - nama eva etat. Yet the words of the text have the unique power not only to prepare us but finally awaken us to our true nature, which is Infinite Bliss - Bhumaiva Sukham.
Swamini Vimalananda has added relevant notes to make the subject easier to grasp.