先秦古禮自喪及祭所用之「主」，乃木製象神物件，藉以事奉先人。漢、晉經師指出「主狀正方，穿中央、達四方」，其形構特殊，歷來卻幾乎未見說解。本文認為上述主狀與晚商亞字形大墓應頗有關聯。亞字形初源自先民觀測天地形成的認知圖象，既投射於古宗廟、明堂等禮制建築佈局，又複製於晚商四墓道的王公大墓，甚且在商周彝銘呈現謎樣的「亞」形符號。而神主既供祖先妥靈，亦具體而微地模擬亞形。自晚商以迄西漢，亞字墓應屬帝王所有，與此呼應的則是《公》、《穀》家說：「天子、諸侯有主」而「大夫、士無主」。相關佐證如：1、古時「黃帝四面」的傳說，2、《儀禮•覲禮》壇祀「方明」，3、《周禮•典瑞》斂用「駔圭」，俱可與「主」制、「亞」形連類並觀。要之，主狀附帶的亞字形穿孔，不只象徵死者靈魂駐居「神聖的中心」，四出延展的通道，亦寓含人王君臨大地的權威感及道通天地的心靈意識。

This article, by reviewing previous records and studies on the significance and meaning of the Ya（亞） character shape, proposes that the shape of the “seat of soul” in Confucian classics is closely associated with the Ya character shaped tombs of the emperors and dukes mostly located in the desolate capital city of late Shang Dynasty. Ya character shaped tombs can be traced back to ancient China symbolic of the creation of the universe. Similar shapes are found within temples, the layout of imperial assembly halls（明堂）, or in the tombs of the emperors and dukes. Ancient bronze artifacts also show these mysterious Ya shaped symbols. The seat of soul appears to mimic the sacred Ya character shape. It is usually a wooden object representing the dead, which is typically square in shape, with a hole in the middle and four paths stretching outwards in order to house the spirits of the departed. The hole in the middle is the anchoring point demonstrating the sacred center where the departed resides. The stretching four paths symbolize the gateway and the sense of authority of the emperors and dukes, and their spiritual awareness and connection with the cosmos. Moreover, this article cites sources from the classics for further supporting evidences, including “four-face Yellow Emperor”（黃帝四面）, “Fang Ming”（方明） and “Zu Gui”（駔圭）.