I have already said that these castes are a hierarchy. Brahmins are at the top, while there are some castes which are untouchable and are at the bottom. Though there are castes of innumerable gradations, it should be remembered that it is practically impossible for individuals to change their caste.
The internal structure of a caste is not quite simple. Castes are again divided into several groups called gotras. These gotras are exogamous. They are something like the Roman Gens. All persons who belong to a certain gotra, like Kaushika or Garga, are supposed to be persons descended from the mythical ancestor Kaushika or Garga. No family may marry with a family of the same gotra. In general all the gotras or exogamous groups have the same status in the castes. But there are some castes where such is not the case. In some parts of India there is hypergamy. Certain groups of families in a caste are considered higher than the rest, and it is customary that women in the inferior groups should seek to marry with men in the superior groups, but not vice versa. This kind of custom is confined mostly to Northern India, and is found in its worst form in Bengal.
Castes are to be distinguished in one point from the hereditary classes, like those of Europe who marry among themselves, that the people who are not born in those classes could rise to that class by their ability, while nobody can go into a higher caste. Among classes who marry among themselves, marriage outside the class is prevented by sentiment and not by hard and fast rules. Marriage outside the class in Europe might be rare or invalid, but in India if it is contracted outside the caste it is a sacrilege.
