Progressive Stages of Meditation by Khenpo Tsultrim is one of his most popular books. It is hard to get so we offer it as a PDF.

Thrangu Rinpoche with Khenpo Tsultrim have taught the four regents of the Kagyu school of Buddhism and in this book Khenpo Tsultrim presents the main school of Buddhist philosophy and their progressive development of philosophy of the true nature of phenomena.

In this book Khenpo Tsultrim Rinpoche discusses in detail Foundation School (Hinayana) approach to existence and view of emptiness. Then he discusses the second major school of Mind-only or Chitamatra school that all phenomena are mind. Next, he discusses the two Middle-way (Madhayanaka) schools and their different approach to the emptiness of phenomena. These are the Svatantrica and the Prasangika schools. Finally, he devotes a chapter to the Shentong approach to emptiness which involves luminous clarity and buddha nature which is most relevant to the meditator.

Khenpo Tsultim Rinpoche was a yogi for many years and so his explanations are very concise and easy to understand which is in contrast to the lengthy treatises on emptiness of the Middle-way approach.