Discussion of the dream's navel has so far turned on the scene of Irma's throat and on the affect lodged there. This paper proposes to move it to a paragraph the commentaries do not cite: the one in which Freud describes his own network of associations as a meshwork with no definite ending, out of which the wish grows like a mushroom from its mycelium. That paragraph says of one and the same place that it produces the content and that it teaches nothing about it. A single term, borrowed from mathematics and defined on the spot — obstruction — allows both statements to stand without striking out either, and answers the questions Derrida left open. Two consequences are drawn and submitted to test. This record contains the same paper in two versions: English (primary) and French (original). — Ce dépôt contient le même texte en deux versions : anglaise (principale) et française (originale).