The sound of the birds

"If you hear the sound of the birds outside--if you really hear them--then you'll hear Guru Rinpoche's mantra. If you hear this way, you will know the results of the development and completion stages--and Dzogchen is possible."

p449 Wisdom Eccentrics, Kyabjé Künzang Dorje Rinpoche, Ngakpa Chögyam, Aro Books, Inc, 2011, 978-0965394864