We have already seen (p. 86) that on occasions of special licence connection between brother and sister, though otherwise strictly tabooed, may be temporarily permitted. It seems to be pretty generally agreed among anthropologists that these occasions are of the nature of reversions to a condition of affairs that was once comparatively frequent, if not indeed quite general[86]. There are in fact numerous indications that such brother-sister connections were, among certain peoples at any rate, the rule rather than the exception. H. L. Morgan, to whose credit lies the discovery of the so-called classificatory system of relationship, thinks indeed that a group marriage between own brothers and sisters was the earliest kind of restriction upon absolute promiscuity and constituted the basis of the oldest form of the human family[87]. The evidence for the really primitive character of any such family has been seriously disputed in more recent writings[88]; but the frequent occurrence of temporary or permanent brother-sister unions among both primitive and more advanced peoples would seem to be beyond dispute. Thus the incest of brother and sister is said to be, or to have been, common among the Antambahoaka of South East Madagascar[89], among many tribes of Brazil[90], in Cali[91] (Colombia), Tenasserim[92] (Burma), Mexico[93] and many other places. The ancient Persians seem to have permitted incest of this kind, though Herodotus remarks with reference to the marriage of Cambyses to his sister that this was not a usual procedure[94]. In Egypt, however, such connections were not only admitted but approved, marriage between brother and sister being there regarded as the "best of marriages" and acquiring "an ineffable degree of sanctity when the brother and sister who contracted it were themselves born of a brother and sister, who had in their turn also sprung from a union of the same sort"[95]. Even in Greece a similar practice does not seem to have been unusual, for, if we may believe Cornelius Nepos[96], no disgrace attached to Cimon's marriage with his sister Elpinice, since his fellow-citizens had the same custom. Among the Jews too, the prophet Ezekiel[97] complains of the occurrence of this form of incest. Primitive customs, it is now generally agreed, are apt to persist in the case of royal families long after they have ceased to be observed by the common people; and the persistent brother and sister marriages among the Ptolemies of Egypt and the Incas of Peru, as well as the existence of similar practices among reigning families in primitive peoples of recent times[98], afford further evidence of the former widespread occurrence of brother-sister unions. [Sidenote: Repression of, and desire for such incest]