晚清的空間概念經歷重大衝擊，地理想像的轉變影響到文學表現，本文以《癡人說夢記》為主要的分析對象，探討小說如何在「地理大發現」的衝擊下產生空間的變革。首先，本文從敘事中的父子的空間想像，論析傳統「仙人島」如何轉變到具有現代性視野的「鎮仙城」以及其意義；接著，論證新地理觀如何衝擊到小說的敘事，晚清後起的地理與政治概念如「五大洲說」、「國家」等進入了小說版圖，人物在逃亡時以天下為家，可是接著又很弔詭地發現天下無家，進而產生虛化的空間──烏托邦；本文進一步分析此虛化空間所展現的視野，科技與民主介入了此空間，成為往後五四「德先生」與「賽先生」的先聲；最後，本文指出當烏托邦方案建構出來時，卻也一體兩面地步向反烏托邦的方向，自我消解了原初的理想性，出現創作動機與書寫結果的斷裂。

In the late Qing era, the concepts of space were confronted with a changing geographical imagination that in turn affected literary expression. Focusing on Dream Talk of an Imbecile (Chiren shuo mengji), this article discusses the presentation of spatial transformation in the late Qing era under the impact of the “Great Age of Discovery.” First of all, it tracks the spatial imagination of the father-son relationship in the novel, thus exploring the shift from the traditional “island of immortals” (xianren dao) towards a modern vision of the “town of suppressed immortals” (zhen xian cheng). How did a new geographical vision – concepts such as the five continents and the nation-state – enter the novel’s space and affect its narrative? The characters must discover that tianxia, which they had taken granted for their home, does not at all belong to them; searching for a route of escape, they construct a new surreal space: Utopia. The article goes on to analyze the visual representation of this surreal space: thus enter science and democracy, precedents of Mr. Democracy and Mr. Science of the May Fourth period. Yet when the utopian plan is completely laid out, it turns into its own other, to an anti-utopia: disposing its original ideal and causing a rift between the writing motive and its written result.