The customary term for such a faculty in literature of the Romantic period
is imagination. Yet, the connotations of Walton's diction do not aspire
to such a level of import, a "day dream" implying something less
substantial than a reverie, which itself signifies a mental state much less
imposing than a vision. This implicit deflation of the power or value of
the imagination will become a thematic undertone in the novel.