The development of a theory of drama progressed in the closest relation to the general theory of poetics, for the Indian theory of poetry does not admit any distinction in essence between the aesthetic pleasure produced by the drama and any other form of poetry. Thus we find in Abhinavagupta in full application to the drama the theory of suggestion, Dhvani, as the essence of poetry, which appeared in strength about A.D. 800 and was rendered popular by Ānandavardhana (A.D. 850) and by Abhinavagupta himself in his comment on the Dhvanyāloka of the former. Attacked by Mahiman Bhaṭṭa, author of the Vyaktiviveka (A.D. 1050), the doctrine was again developed with special care by the Kashmirian Mammaṭa [608] at the close of the eleventh century. In slightly varied forms it appears in Vidyānātha, Vidyādhara, and Viçvanātha. Apart from this important development, which, however, has no special application to the drama, there is little progress in the course of the literature. The later authorities are bound by the authority of the Nāṭyaçāstra; they repeat unintelligently its descriptions of literary forms such as the Ḍima, the Samavakāra, the Īhāmṛga, the Vīthī, and the An̄ka, which had ceased to be in popular use, if indeed the definitions of the Nāṭyaçāstra were not merely hasty generalizations from a single play or so in every one of these cases. The most that they do is to omit or to vary details, but not in independence; normally the changes can be traced to variants in the text of the Çāstra or to maxims current under Bharata’s name, though not included in the Çāstra as we have it. Often the authors differ in the definition of terms in the Çāstra which, as often in Sanskrit technical phrases, present ambiguity and admit of various renderings. These divergences are especially frequent in the long lists of characteristics and ornaments or the different means of effecting dramatic results; the Indian love of meaningless subdivision here can indulge itself to its fullest and least profitable extent. A rich variety of such ambiguities is apparent in the verses in which the Agni Purāṇa [609] describes the drama, including dancing and the mimetic art, true to its aim to constitute itself a treasure-house of all learning, popular as well as divine. The chief value of the work is the occasional light which it throws on the variants in the text of the Çāstra, and its comparative antiquity, for it is cited in the Sāhityadarpaṇa and is probably some centuries older. 2. THE NATURE AND THE TYPES OF THE DRAMA