Le masque vide (The Empty Mask) by René Magritte, 1928. Oil on canvas, 81.2 cm x 116.2 cm. National Museum, Wales. Currently on loan to the Tate Gallery in London.

From the National Museum website:

In his essay Words and Images, published in 1929, the Belgian Surrealist Magritte observed that each image ‘suggests that there are others behind it’. Viewed through a freestanding frame of irregular shape, these images are a sky, a lead curtain festooned with sleigh bells, a house façade, a sheet of paper cut-outs, a forest and a fire. The title evokes the fear of the invisible which pervades the artist’s work and reflects the Surrealists’ fascination with the subconscious.