For none of the native religious works has one a certain date. Nor is there for any one of the earlier compositions the certainty that it belongs, as a whole, to any one time. The Rig Veda was composed by successive generations; the Atharvan represents different ages; each Br[=a]hmana appears to belong in part to one era, in part to another; the earliest S[=u]tras (manuals of law, etc.) have been interpolated; the earliest metrical code is a composite; the great epic is the work of centuries; and not only do the Upanishads and Pur[=a]nas represent collectively many different periods, but exactly to which period each individually is to be assigned remains always doubtful. Only in the case of the Buddhistic writings is there a satisfactorily approximate terminus a quo, and even here approximate means merely within the limit of centuries. Nevertheless, criteria fortunately are not lacking to enable one to assign the general bulk of any one work to a certain period in the literary development; and as these periods are, if not sharply, yet plainly distinguishable, one is not in so desperate a case as he might have expected to be, considering that it is impossible to date with certainty any Hindu book or writer before the Christian era. For, first, there exists a difference in language, demarcating the most important periods; and, secondly, the development of the literature has been upon such lines that it is easy to say, from content and method of treatment, whether a given class of writings is a product of the Vedic, early Brahmanic, or late Brahmanic epochs. Usually, indeed, one is unable to tell whether a later Upanishad was made first in the early or late Brahmanic period, but it is known that the Upanishads, as a whole, _i.e._, the literary form and philosophical material which characterize Upanishads, were earlier than the latest Brahmanic period and subsequent to the early Brahmanic period; that they arose at the close of the latter and before the rise of the former. So the Br[=a]hmanas, as a whole, are subsequent to the Vedic age, although some of the Vedic hymns appear to have been made up in the same period with that of the early Br[=a]hmanas. Again, the Pur[=a]nas can be placed with safety after the late Brahmanic age; and, consequently, subsequent to the Upanishads, although it is probable that many Upanishads were written after the first Pur[=a]nas. The general compass of this enormous literature is from an indefinite antiquity to about 1500 A.D. A liberal margin of possible error must be allowed in the assumption of any specific dates. The received opinion is that the Rig Veda goes back to about 2000 B.C., yet are some scholars inclined rather to accept 3000 B.C. as the time that represents this era. Weber, in his _Lectures on Sanskrit Literature_ (p. 7), rightly says that to seek for an exact date is fruitless labor; while Whitney compares Hindu dates to ninepins--set up only to be bowled down again.