Sleeping saint is the story of a subversive, sensual masterpiece

It's a cosy tradition at the National Gallery to showcase one of its Christmassy paintings at this time of year - a Nativity, or an Adoration of the Magi perhaps.

- Jonathan Jones

This year's religious masterpiece is different. Parmigianino's tall yet narrow The Vision of St Jerome is wild, quirky and gets more subversive the longer you look at it. For one thing, there is a female nude hidden in this devotional scene. Parmigianino has changed the gender and aged her - but there's no mistaking his quotation of one of the most sensual paintings in the European canon.

The Vision of St Jerome gets its title from the sleeping figure of the hermit Jerome lying under a rocky overhang in a leafy bower by a pool. Parmigianino paints him from an unexpected angle: feet towards us, head flung back, his body at once vertical and horizontal as he thrusts his loins in your face, his body forcing itself out of the picture into three-dimensional space.