The Mahayana path of Buddhism requires the development of vast loving-kindness and compassion. The foundation for developing impartial compassion for all sentient beings is based on understanding the emptiness of self and the emptiness of phenomena.

In Shentong and Rangtong Thrangu Rinpoche begins with a lucid description of the four major schools of Buddhism and their tenents. Each school had its own view of reality and Rinpoche describes the similarities and differences of these views.

The Middle-way path had two important schools in Tibet: the Shentong and the Rangtong. In the discussion of the Rangtong, Rinpoche shows how important it is to understand the emptiness of persons and of phenomena because this understanding helps develop an accurate view of the world and thus how to proceed in one's practice.

In the discussion of Shentong, Rinpoche describes the empty, luminous clarity of mind and how this is developed in meditation. This clarity is also closely related to understanding Buddha-nature and meditation in the Vajrayana.

Thrangu Rinpoche bases this discussion on Jamgon Kongtrul's encyclopedic text The Treasury of Knowledge. If you liked Khenpo Tsultrim's Progressive Stages of Meditation you will like this book because it is the same topic but in much, much more detail and tied more to how this topic relates to one's practice.