But the offence of the fifth sin, marrying below one's caste, or the marriage of widows, seems as rank as ever. Upon these points, rather, the force of caste seems concentrating. The marriage of widows will be considered when we come to discuss the social inferiority of woman in India. To marry within one's caste promises to be the most persistent of all the caste ideas. The official observation is that "whatever may have been the origin and the earlier developments of caste, this prohibition of mixed marriages stands forth now as its essential and most prominent characteristic. The feeling against such unions is deeply engrained." And again, a second pronouncement on caste: "The regulations regarding food and drink are comparatively fluid and transitory, while those relating to marriage are remarkably stable and absolute."[16] The pro-Hindu lady, already referred to, also agrees. "Of hereditary caste," she says, "the essential characteristic is the refusal of intermarriage."[17] Even Indian Christians are reluctant to marry below their old caste, and value a matrimonial alliance with a higher. To that residuum of caste, when it becomes the residuum, one could not object. The Aryan purity of the stock may be a fiction, as authorities declare it to be in the great majority of castes and in by far the greater part of India; but given the belief in the purity of blood, the desire to preserve it is a natural desire. If one may prophesy, then, regarding the fate of the caste system under the prevailing modern influences, castes will survive longest simply as a number of in-marrying social groups. To that hard core the caste idea is being visibly worn down. [Sidenote: Support of caste by British authorities.]