大唐西域記 2.16

2.16

若夫族姓殊者，有四流焉：一曰婆羅門，淨行也。守道居貞，潔白其操。二曰剎帝利，王種也（舊曰剎利，略也）。奕世君臨，仁恕為志。三曰吠奢（舊曰毘舍，訛也），商賈也。貿遷有無，逐利遠近。四曰戍陀羅（舊曰首陀，訛也），農人也。肆力疇壠，勤身稼穡。凡茲四姓，清濁殊流，婚娶通親，飛伏異路，內外宗枝，姻媾不雜。婦人一嫁，終無再醮。自餘雜姓，寔繁種族，各隨類聚，難以詳載。

With respect to the division of families, there are four classifications. The first is called the Brahman (Po-lo-men), men of pure conduct. They guard themselves in religion, live purely, and observe the most correct principles. The second is called Kshattriya (Tsa-ti-li), the royal caste. For ages they have been the governing class: they apply themselves to virtue (humanity) and kindness. The third is called Vaisyas (Fei-she-li), the merchant class: they engage in commercial exchange, and they follow profit at home and abroad. The fourth is called Sudra (Shu-t'o-lo), the agricultural class: they labour in ploughing and tillage. In these four classes purity or impurity of caste assigns to every one his place. When they marry they rise or fall in position according to their new relationship. They do not allow promiscuous marriages between relations. A woman once married can never take another husband. Besides these there are other classes of many kinds that intermarry according to their several callings. It would be difficult to speak of these in detail.