在文學和文化研究領域中，幽靈的概念已被廣泛引申為他者（如土著、移民、罪犯、少數族裔、邊緣人)，被壓迫的、不可見的、被消音的族群以及歷史，近年來受到德希達《馬克思的幽靈》一書的啟發，陸續有研究強調霸權永遠無法驅逐被壓抑的幽靈，因此這些幽靈會不斷纏繞當下，迫使主體反思並追求正義的可能。但是，纏繞主體的幽靈往往處於邊緣，無法被看見以及被理解，因此，本文將提出「靈媒」此一概念，證明它不僅作為連結自我與他者，當權者與被壓迫者、文明與蠻荒、主流與非主流之間的中介者， 也可以被視為企圖建立多元社會的原則與態度，提供不同情境下對立與鬥爭的解決之道。 筆者將以南非作家柯慈著名的後殖民作品《等待野蠻人》為例，分析書中主角，即管理帝國邊界的地方官，如何在面臨帝國對土著的剝削和酷刑中，以及與野蠻人的交涉中，重新檢視自我身分和帝國二元論述的正當性，進而轉換立場，扮演起靈媒的角色；由於地方官在思想和語言上還是受制於帝國的固有思維，因此無法真正了解野蠻人的歷史、語言與想法，但透過深入蠻荒、遭逢酷刑以及夢境等脫離主體意識的過程 (trance) 以及消極反抗（negation) 和誤讀 (mistranslation) 等策略，主角被動地保留及傳達了野蠻人的聲音，並赤裸地呈現帝國論述本身的幽靈性，筆者將稱他為「被動的靈媒」 (the passive medium)，並深入探討此一特定概念如何提供讀者另一種自我與他者對話的模型與希望。

Ghosts are figuratively roaming in J. M. Coetzee’s well-known postcolonial novel, Waiting for the Barbarians, which is set in an undefined time full of strife and unrest. In the novel, being mysterious and threatening to the Empire, the barbarians represent the spectral others. This paper is concerned with the question of how to approach the figurative ghosts of the barbarians and deal with their haunting when they usually appear in a horrified, irrational or obscure way. I will suggest that the concept of a medium, which refers to a person who acts as go-between between the living and the spiritual world, can be used more figuratively as an attitude that presupposes a mode of negotiation through which a person approaches the spectral other and establishes a mutual understanding with it. In addition, I will argue that the protagonist, the Magistrate, plays the role of “passive medium,” which refers to a person who originally belongs to the class of the authorities, or is restricted to the dominant cognitive frame, but is haunted by the foreignness of the repressed other and forced to establish identification with this ghostly other. By examining how the Magistrate experiences his emotional and social ambivalence in his encounter with his inner otherness as well the external otherness, I investigate how the concept of passive medium functions productively to challenge the hierarchy between the Empire and the barbarians, self and other, and to re-imagine a dialogic world to come.