 There is a latent tension within tathagatagarbha theory, as Fazang understands it. This is the tension between conceptualizing ultimate reality as tathagatagarbha and conceptualizing tathagatagarbha as ineffable. This is why Fazang ranks the Final Teaching of the Mahayana as inferior to a fourth teaching, which he calls the Sudden Teaching. This is the teaching of Vimalakirti, from the Vimalakirti Sutra, who, in responding to a request to characterize ultimate reality, answers with silence. This is superior to the Final Teaching of Mahayana, according to Fazang, because the only way to succeed at conceptualizing the ultimate nature of reality is to refuse to conceptualize in the first place. 