[Various forms of exogamy.] 2. Before discussing the possible origin of exogamy it may be well to explain some of its various forms, of which numerous details, so far as it has been possible to ascertain them, are given in the subsequent pages. We have, then, first the Brâhmanical law of exogamy. Persons are forbidden according to the Sanskrit law-books, to intermarry, who are related as sapindas, that is to say, who are within five degrees of affinity on the side of the father. The person himself is counted as one of these degrees, that is to say, two persons are sapindas to each other, if their common ancestor being a male is not further removed from either of them than six degrees, or four degrees where the common ancestor is female. [33] [The gotra.] 3. These prohibitions form a list of prohibited degrees in addition to the ordinary formula, which prevents a Brâhman or a member of those castes which ape the Brâhmanical organization, from marrying within his gotra or exogamous section. The word gotra means “a cow-pen,” and each bears the name of some Rishi or mythical saint, from whom each member of the group is supposed to be descended. Theoretically all the Brâhmanical gotras have eight great ancestors only—Viswamitra, Jamadagni, Bhâradvaja, Gautama, Atri, Vasishtha, Kasyapa, and Agastya. These occupy with the Brâhmans pretty much the same position as the twelve sons of Jacob with the Jews; and only he whose descent from one of these mighty Rishis was beyond all doubt could become a founder of a gotra. [34] The next point to remark is that, as Mr. Ibbetson [35] has pointed out, the names of many of the founders of these gotras appear among the ancient genealogies of the earliest Râjput dynasties, the Râjas in question being not merely namesakes of, but distinctly stated to be the actual founders of the gotra; and it would be strange if enquiry were to show that the priestly classes, like the menials, owe their tribal divisions to the great families to whom their ancestors were attached.