Tristasis is an ontological system whose ground is neither a being, nor a subject, nor a first principle, but distinction, a primitive that falls under no genus. The standing of a distinction is named holding. To be, on this premise, is to endure while continuing to be distinguished, and every existent is held before it becomes the object of any gaze. A single distinction has two ends, and they act as forces: taxis, the pull toward marking-out and order, and chysis, the pull toward dispersal; the gap between them, never closed to the end, is named diapherensis. The alteredness of holding that remains after the meeting of configurations is a trace, and traces marked out in sequence yield time, while traces marked out as co-presence yield space. Where, among the traces of a holding, there appears the trace of the holder itself, a fold arises, and with it thinking and what is customarily called the "I"; feeling, as the self-touching of what endures, is older than the fold and relates the human being to all that lives. The materialism of the system is named irrational because holding cannot be derived from form, what is felt cannot be produced by thinking, and there is no external point from which the order of matter could be surveyed in its entirety. The system is built in the modality of assumption: it does not prove its ground, but shows what becomes explicable once that ground is accepted.