The Rokeby Venus

The object
Venus's reflection in the small mirror that Cupid is holding
The story

From the angle at which Venus reclines and the angle at which Cupid holds the mirror, the mirror cannot physically be reflecting her face. It should reflect her shoulder or her chest. Velázquez painted an impossible reflection: a face turned forward to meet the viewer's eye, where geometry demands no face at all. He also painted it slightly out of focus, as if Venus herself cannot quite see her own image. Now at The National Gallery, London @nationalgallery

The reel
The painting
The Rokeby Venus, Diego Velázquez