One of the well-known polemical writers of Advaita metaphysics, Ānanda-bodha (11th cent. A.D.) (also called Ānanda-bodhācārya and Ānandabodha Bhaṭṭārakā-cārya) a disciple of Vimuktātman of the Iṣṭisiddhi fame (10th cent. A. D.) has four works to his credit: Nyāyamakaranda, Nyāyadīpāvalī, Pramāṇamālā and Śabda-nirṇaya Vyākhyā. The first of these is the most celebrated and has been commented upon by Citsukha (13th cent. A. D.). The special features of this work are: refutation of the Sāṅkhyan theory of multiplicity of selves and the apparent difference of objective entities; the theory that everything other than Brahman is mithyā (false) since it is dṛśya (perceived); a new defini-tion of mithyātva (falsity) viz., sadbhinnatvaṁ mithyātvam (falsity is being diffe-rent from the real); that avidyā is positive in the sense it is non-negative; that the cessation of avidyā is an entity of a fifth category, different from sat (real), asat (unreal), sad-asat (real-unreal) and anirvacanīya (indefinable).