卿大夫士爵在西周并不存在,大约在两周间或东周初才演生出来。“层级化”与“席位爵”概念,有助于辨析这个问题。“层级化”意谓首先出现的是官职,随后逐渐进化出职官层级。西周职官已经初步层级化了,体现为“卿士─师尹─御事”,当时人们依此、而不是依“卿─大夫─士”来称述职官,因为当时尚无“卿─大夫─士”爵列。原生意义的“爵位”,是氏族会食时执爵而饮的席位,这个意义上的“爵”可称“席位爵”,以区别于作为官员秩次的“品位爵”。乡饮酒礼的坐席分三等:士(即子弟)的堂下站位,大夫(即大人、父老)的堂上坐席,“卿”(即族长、乡老)的主人之席。若官员前来观礼,则要按三等命数,分别在士之位、大夫之位及贵宾之位就坐。这三等席位之法及三等席位之名,被朝廷飨燕之礼袭用,其时三个层级的官员分别在三等席位就坐,由此卿、大夫、士称谓发展为官员秩等之称,变成“品位爵”。

It is generally acknowledged that the ranking system of Jue (爵制), including the ranks of minister(卿),grand master (大夫) and serviceman(士),didn't exist in the Western Dynasty. This system didn't make its appearance until the end of the Western Dynasty or the beginning of the Eastern Dynasty. The concepts of hierarchization (层级化) and ranking of Jue by seating (席位爵) are helpful to the analysis of this issue. Hierarchization is in the sense that there first appeared official posts, which gradually evolved into hierarchical officialdom. In the Western Dynasty, the official posts were initially hierarchized, which was presented in the descending order of ranking: Qin shi(卿士), Shi yin(师尹),and Yu shi(御事). At that time, people referred to the series of official posts by way of this ranking, instead of the ranking system of Jue: minister, grand master and serviceman. The ranking of Jue was originated from the seating for the members of a clan when they had a dinner holding their jue which was a wine vessel. In this sense, the ranking system of Jue was the ranking of Jue by seating (席位爵), which was different from the ranking of Jue by official status (品位爵). The evolution of the minister-master-serviceman hierarchy was closely related to the drinking festivity. The seating for the drinking rites in the rural district (乡饮酒礼) was divided into three classes: the patriarch of the clan occupied the host seat; the elders of the clan took seats on the court; and the young men stood off the court. If officials came to attend the drinking rites,they should take their seats in correspondence with their honors: the distinguished guest seat, the grand master's seat and the serviceman's seat. The imperial court copied this three-class seating arrangement in its banquets, and the hierarchy of minister grand master and serviceman evolved into official ranking and became the ranking system of Jue by seating.