The ceremonial of ancestor-worship was especially elaborated, and developed a special literature of its own, extending from the Vedic period to the legal Compendia of the Middle Ages. The Çraddha-kalpa of Hemadri comprises upwards of 1700 pages in the edition of the Bibliotheca Indica. The above is the briefest possible sketch of the abundant material of the Grihya Sutras, illustrating the daily domestic life of ancient India. Perhaps, however, enough has been said to show that they have much human interest, and that they occupy an important place in the history of civilisation. The second branch of the Sutra literature, based on tradition or Smriti, are the Dharma Sutras, which deal with the customs of everyday life (samayacharika). They are the earliest Indian works on law, treating fully of its religious, but only partially and briefly of its secular, aspect. The term Dharma Sutra is, strictly speaking, applied to those collections of legal aphorisms which form part of the body of Sutras belonging to a particular branch (çakha) of the Veda. In this sense only three have been preserved, all of them attached to the Taittiriya division of the Black Yajurveda. But there is good reason to suppose that other works of the same kind which have been preserved, or are known to have existed, were originally also attached to individual Vedic schools. That Sutras on Dharma were composed at a very early period is shown by the fact that Yaska, who dates from near the beginning of the Sutra age, quotes legal rules in the Sutra style. Indeed, one or two of those extant must go back to about his time. The Dharma Sutra which has been best preserved, and has remained free from the influence of sectarians or modern editors, is that of the Apastambas. It forms two (28-29) of the thirty sections of the great Apastamba Kalpa Sutra, or body of aphorisms concerning the performance of sacrifices and the duties of the three upper classes. It deals chiefly with the duties of the Vedic student and of the householder, with forbidden food, purifications, and penances, while, on the secular side, it touches upon the law of marriage, inheritance, and crime only. From the disapprobation which the author expresses for a certain practice of the people of the North, it may be inferred that he belonged to the South, where his school is known to have been settled in later times. Owing to the pre-Paninean character of its language and other criteria, Bühler has assigned this Dharma Sutra to about 400 B.C.