Lectures on the Sūtra of the Collection of the Father and Son (Pitāputrasamāgamanasūtra), Part 63

Except for the tathāgatagarbha, all dharmas are empty

Material form is itself empty, formed from the four great seeds of earth, water, fire, and wind; earth, water, fire, and wind are themselves empty, and the material world they form is therefore empty, unattainable. The eye faculty is likewise empty, unattainable, and should not be clung to. Originally there is no eye base and no eye faculty; the four great seeds are transmitted forth, and from a state of nothing whatsoever the eye faculty is born, and in the end it returns to nothing whatsoever. Both the process of formation and the result are empty. A dharma that arises and ceases, a dharma that is nothing whatsoever, is empty. What dharma is not empty? Our tathāgatagarbha mind is not empty. Do not be misled by the fact that He is formless and without characteristics—He is constantly giving rise to mind, constantly functioning, constantly manifesting the myriad dharmas for us. Apart from Him, all dharmas are empty.