This article explores the various kinds of surfaces that recur in Henry James’s writings in the forms of imagery, characterization, narrative content, and linguistic style. It focuses especially on the surfaces that suggest and make possible spaces of ‘undetermined capacity’. Reading a range of texts, including The Europeans, ‘The Real Thing’, ‘The Jolly Corner’, his notebook entries, and those in which he probes the connections between the creative process and the ‘act of life’, this essay shows how James unsettles the metaphysical assumption that depth/substance holds more meaning than surface/appearance. Although James is known for his investigation into the inner life of the mind, the surface is a key image in his conception of artistic creation. It is an inextricable part of how James makes the ineffable or the unfathomable – blanks, voids, possibilities – gain imagined substance. This essay argues that the obscure but charged spaces of ‘undetermined capacity’ that his texts generate, through the representation of surfaces, enable the creativity of the writer as well as the imagination of the reader. These ideas are applied to the potentiality of a literary text.