This article examines the relationship between British Idealist philosophy and modernist form, particularly the stream of consciousness technique. Idealism was ascendant from the 1870s to the 1920s, and the writer/philosopher May Sinclair participated in its conceptual discourse, finding the British Idealists’ contention that time is unreal an especially valuable insight for her literary agenda. For many of the idealists, time is unreal in the sense that multiple temporal series coexist within the universe or atemporal “Absolute.” This idea, which was debated in the journal Mind and elsewhere, played a significant role in the literary conception of “stream of consciousness,” a term first applied to literature by Sinclair in 1918. Considering the interplay of literature and philosophy during this period expands our understanding of the genealogy of modernist form and its effects. In particular, in evoking an experience of the timeless, for Sinclair stream of consciousness draws together authors, characters, and readers, generating among them complex investments, both ethical and ontological.