Closely connected with the Mahabharata is a distinct class of eighteen epic works, didactic in character and sectarian in purpose, going by the name of Purana. The term purana is already found in the Brahmanas designating cosmogonic inquiries generally. It is also used in the Mahabharata somewhat vaguely to express "ancient legendary lore," implying didactic as well as narrative matter, and pointing to an old collection of epic stories. One passage of the epic (I. v. 1) describes purana as containing stories of the gods and genealogies of the sages. In Book XVIII., as well as in the Harivamça, mention is even made of eighteen Puranas, which, however, have not been preserved; for those known to us are all, on the whole, later than the Mahabharata, and for the most part derive their legends of ancient days from the great epic itself. Nevertheless they contain much that is old; and it is not always possible to assume that the passages they have in common with the Mahabharata and Manu have been borrowed from those works. They are connected by many threads with the old law-books (smritis) and the Vedas, representing probably a development of older works of the same class. In that part of their contents which is peculiar to them, the Puranas agree so closely, being often verbally identical for pages, that they must be derived from some older collection as a common source. Most of them are introduced in exactly the same way as the Mahabharata, Ugraçravas, the son of Lomaharshana, being represented as relating their contents to Çaunaka on the occasion of a sacrifice in the Naimisha forest. The object of most of these legendary compilations is to recommend the sectarian cult of Vishnu, though some of them favour the worship of Çiva. Besides cosmogony, they deal with mythical descriptions of the earth, the doctrine of the cosmic ages, the exploits of ancient gods, saints, and heroes, accounts of the Avatars of Vishnu, the genealogies of the Solar and Lunar race of kings, and enumerations of the thousand names of Vishnu or of Çiva. They also contain rules about the worship of the gods by means of prayers, fastings, votive offerings, festivals, and pilgrimages. The Garuda, as well as the late and unimportant Agni Purana, practically constitute abstracts of the Mahabharata and the Harivamça. The Vayu, which appears to be one of the oldest, coincides in part of its matter with the Mahabharata, but is more closely connected with the Harivamça, the passage which deals with the creation of the world often agreeing verbatim with the corresponding part of the latter poem.