Lecture Notes on the Sūtra of the Collection of the Father and Son (Pitāputrasamāgamanasūtra) (134)

All dharmas are entirely empty and tranquil; this is called the door of emptiness liberation. Emptiness itself has no mark of emptiness—the dharma of emptiness inherently possesses no mark of emptiness; it is merely a name and concept, without any mark. Emptiness has no appearance of emptiness; there is not a single mark at all, not even the mark of emptiness. This is called the door of signlessness liberation. If all marks are gone, what else would we long for? What wishes and aspirations would remain? All dharmas are empty, so what more could you hope for? With no aspirations left, this is called the door of wishlessness liberation. When these three dharmas are practiced in accord with emptiness, the mind is liberated; this is called the three doors of liberation. Emptiness, signlessness, and wishlessness—this "wish" refers to longing, to aspiring for results, to the vows one makes and issues. Since everything is nonexistent, whatever one grasps at is empty; even becoming a Buddha is ultimately empty. The Diamond Sutra has taught that the fruition of buddhahood cannot be attained. If even the fruition of buddhahood cannot be attained, what else could you wish to obtain? No matter what we think we have gained, upon careful analysis and examination, we know that nothing has been gained—there is fundamentally no one who gains, let alone any dharma that is gained.