India is a literary country and naturally so great a change as the transformation of the old religion into theistic sects preaching salvation by devotion to a particular deity found expression in a long and copious literature. This literature supplements and supersedes the Vedic treatises but without impairing their theoretical authority, and, since it cannot compare with them in antiquity and has not the same historic interest, it has received little attention from Indianists until the present century. But in spite of its defects it is of the highest importance for an understanding of medieval and contemporary Hinduism. Much of it is avowedly based on the principle that in this degenerate age the Veda is difficult to understand,[440] and that therefore God in His mercy has revealed other texts containing a clear compendium of doctrine. Thus the great Vishnuite doctor Râmânuja states authoritatively "The incontrovertible fact then is as follows: The Lord who is known from the Vedânta texts ... recognising that the Vedas are difficult to fathom by all beings other than himself ... with a view to enable his devotees to grasp the true meaning of the Vedas, himself composed the Pâncarâtra-Sâstra."[441] This later sectarian literature falls into several divisions. A. Certain episodes of the Mahâbhârata. The most celebrated of these is the Bhagavad-gîtâ, which is probably anterior to the Christian era. Though it is incorporated in the Epic it is frequently spoken of as an independent work. Later and less celebrated but greatly esteemed by Vishnuites is the latter part of book XII, commonly known as Nârâyaṇîya.[442] Both these episodes and others[443] are closely analogous to metrical Upanishads. The Mahâbhârata even styles itself (I. 261) the Veda of Kṛishṇa (Kârshṇa). The Râmâyaṇa does not contain religious episodes comparable to those mentioned but the story has more than once been re-written in a religious and philosophic form. Of such versions the Adhyâtma-Râmâyaṇa[444] and Yoga-vaśishtḥa-Râmâyaṇa are very popular. B. Though the Purâṇas[445] are not at all alike, most of them show clear affinity both as literature and as religious thought to the various strata of the Mahâbhârata, and to the Law Books, especially the metrical code of Manu. These all represent a form of orthodoxy which while admitting much that is not found in the Veda is still Brahmanic and traditionalist. The older Purâṇas (_e.g._ Matsya, Vâyu, Mârkaṇḍeya, Vishṇu), or at least the older parts of them, are the literary expression of that Hindu reaction which gained political power with the accession of the Gupta dynasty. They are less definitely sectarian than later works such as the Nârada and Liṅga Purânas, yet all are more or less sectarian.