The subject is from a comedy by the playwright, Antonio de Zamora. The timorous Don Claudio, the main protagonist, has been led to believe that his life depends upon keeping a lamp alight.
The inscription in the bottom right contains the first part of two words 'lampara descomunal' (monstrous lamp). These are the words Don Claudio cries aloud while replenishing the lamp with oil.
The composition may have been suggested to Goya by a stage presentation. The picture is one of six scenes of witchcraft painted for the Duke of Osuna and paid for in 1798.