This dissertation attempts to develop the beginnings of a new approach to understanding the significance of modes of thought marginal and/or external to those of the modern West. I call this approach an "anthropology of concepts" because it examines concepts and themes belonging to scriptural, "philosophical," and poetic traditions as concepts rather than, as normally happens in anthropology, in the context of social practices, historical events, or everyday life. I also call it this because it accordingly involves the close reading and interpretation of the written or oral texts in which concepts are articulated. Concepts, when treated this way, retain their capacity to bring about novel understandings of the real, and to engender thereby theoretical perspectives not attainable through more conventional interpretive means. Such an approach may be necessary if the humanities and social sciences are to continue to hold a critical perspective on a world so enclosed that gaining any distance from its basic schemes of thought has become extremely difficult.The present dissertation undertakes such an "anthropology of concepts" in order to elaborate what I intend to be a new theory of the psyche and consciousness. Popularly regarded as one of the founders of the New Age spirituality of the United States, Jane Roberts (1925-1984) was a "channel" (a kind of spirit medium) and visionary mystic who published in the 1960's and 1970's over twenty books that she understood to have been dictated or written through her by different spiritual beings, including one she called "Seth." Although these texts were crucial to the popularization of Western occult ideas about reincarnation, magic, and health that were at the heart of the New Age, Roberts's intellectual curiosity and background as an author of science fiction give her writings a speculative, intellectually reflexive, and even manifestly ontological tone that is reminiscent of certain mystical thinkers and that sets them apart from popular religious discourse. My engagement with Roberts' writings focuses, first of all, on the concepts she and her cohort of personalities articulated in the course of addressing what was for her the most pressing question raised by the decades she spent channeling: how could her experience during her trances of being herself and another self in the same instant of time be possible? Her answer was that such an experience--what she called "other-consciousness"--occurs not through language but when the subject sees itself in the non-sensory, mental images of dreams and the imagination. She was right in the sense that such images, as Jean-Paul Sartre makes clear in Psychology of the Imagination, allow two aesthetic figures or persons to appear as one. My argument is that her claim is significant for showing, surprisingly enough, that contrary to what French philosophy claimed for decades, the other can be brought into and made part of consciousness without being appropriated and consciousness therefore takes a radically altered form. The baseline consciousness of oneself, that is, changes from apperception to a consciousness of oneself as both oneself and another--and even of oneself as a plurality of selves. To make this point, I read concurrently with Jane Roberts' texts the work of Deleuze, showing that she raised in her own fashion some of the same questions about being, time, and the subject as he did, but that the strange context in which she thought led her to furnish significantly different--and now for us, novel--responses to them. Given that a subject that would be at once itself and another would also be both what it actually is and what it otherwise only could have been, I furthermore show how Roberts' work allows one to rethink the Deleuzean (and by implication deconstructive) understandings of the categories of actuality and possibility and another concept--time--to which they are integrally tied. The fact that her writings provide a basis for recasting the thought of such a comprehensive philosopher on matters this fundamental is an indication, I think, of the broad value an anthropology of concepts could hold for humanistic research.