In his metapsychology Freud repeats on several occasions that the unconscious is timeless, that the passage of time does not alter those things which are repressed, and that the perception of the passing of time is one of the characteristics which distinguish the conscious from the unconscious, and later, the ego from the id. Rather than being an afterthought, this assumption by Freud, made right at the start of his career as an inference to the best explanation based on his clinical material, is essential to the overall functioning of psychoanalytic theory. Timelessness, is the necessary cornerstone of psychoanalysis, and one which is derived from the most basic apparatus of perception. Or rather not a cornerstone but an invisible lynchpin, akin to the Pantheon's central occulus: an absence at the centre of the construction, an imperceptible keystone through which the rest of Freud's metapsychology silently channels its weight. Timelessness is the justification for the phenomenon of repression, the explanation for a memory which is both unreliable and somehow eternal; it demands après-coup, fractures chronology and determines the nature of transference. This paper examines the origins of this idea in Freud's use of Kant, and uses examples from Proust.