The Colouring Book stages a problem that is, at its core, a problem of medium. The A4 sheet — printer paper, the most indifferent of surfaces — is proposed not as a neutral support but as a structural condition: a limit that determines, in advance, the terms of artistic production. What the project asks of its contributors is not generosity, though generosity was abundant, but a specific act of formal submission. The work must fit. It must be reproducible without loss. It must arrive, via a domestic inkjet, intact. This is not a minor constraint. It is, in fact, the entire argument. Conceived by Giammaria Biancuzzi and co-curated with Rosella Farinotti under the editorial project Milano Art Guide, The Colouring Book distributed two to three drawings per day across the duration of Italy's 2020 lockdowns, accumulating a corpus of three hundred works by some of the most significant figures in contemporary art — Maurizio Cattelan, Paola Pivi, among many others. Released freely online, the drawings asked to be printed, and then coloured. The second gesture is not decorative. It is constitutive. The work, as distributed, is unfinished by design: it solicits a completion that it cannot control and does not anticipate. In this sense The Colouring Book belongs to a lineage that runs from Eco's opera aperta through the participatory practices of the 1960s — yet it arrives at that tradition from an entirely different direction, not through institutional critique but through epidemic necessity. What the archive reveals, read as a whole, is something neither planned nor curated in the conventional sense: an involuntary iconography of confinement. Gloves, masks, domestic interiors, windows. The motifs recur across artists who did not coordinate, did not consult, did not know what the others were drawing. The collection becomes, in this light, a document — not of individual practice but of a shared perceptual condition, the visual residue of months in which the world contracted to the dimensions of a room. That this residue should take the form of an uncoloured line drawing is not incidental. The line, without fill, without tone, is pure proposition. It waits. So did everyone else.