… I believe that a tanpura is like a bodhi tree for a musician. Relentless practice under its shade can accord musical enlightenment. I understood that shadja is the pivot of all ragas. All the swaras and ragas surge forth and manifest from the spring of shadja. I also realized that sadhana can be fruitful only by constant contemplation of the swara sa. “Sa-dhana” is in fact “Sa-dhyana”.
That beautiful passage is from the autobiography of Pt. Mallikarjun Mansur: Rasa Yatra — My journey in music.