The Buddha Within, the Tathagatagarbha Doctrine According to the Shentong Interpretation of the Ratnagotravibhaga, by S.H. Hookham

The Tathagatagarbha-Buddha Nature is a central concept of Mahayana Buddhism crucial to all living practice traditions of Tibetan and Zen Buddhism. Its relationship to the concept of emptiness has been a subject for seven hundred years. Dr. Hookhams work invetigates the divergent interpretations of these concepts and the way the Tibetan tradition is resolving them.

In particular she does this  with reference to the only surviving indian commentary on the Tathagatagarbha doctrine, the Ratnagotravibhaga. This Text addresses itself directly to the issue of how to relate the doctrine of emptiness (The illusiory nature of the world) to that of the truly existing, changeless Absolute (the Buddha Nature).