Artist: Pieter Paul Rubens (1577-1640) always retained a northern-European robustness, even a peasant vitality, that energises and heats his classical myths, courtly portraits and landscapes. He spent most of his 20s in Italy, making studies of classical art and Renaissance masterpieces by Titian and Raphael. When he set up his studio back in Antwerp, his art had been richly churned into a synthesis of Flemish and Italian art - civilised, but not too civilised. Rubens is one of the supreme painters of emotion; his art feasts on the irrational and the erotic, and includes some of European art's most influential images of violence, turbulence and cruelty.

This is a painting from Rubens's studio. It may have been worked on by Rubens and by his pupil Anthony van Dyck, as well as Jan Wildens (sky and landscape) and Frans Snijders (leaves and fruit). The theme is very Rubens; there is another closely related Rubens painting, The March of Silenus. The depiction of flushed Bacchanalian figures was popular with other Flemish painters.

Subject: In classical myth, Silenus is the teacher and friend of Bacchus, god of wine. In Renaissance art he is depicted as fat, drunk and naked, a bloated lord of the revels, often needing to be helped by his followers. In Titian's Bacchus and Ariadne in the National Gallery, he totters on a donkey, his belly flowing over, his head slumped. Renaissance intellectuals had sophisticated notions of Silenus. Erasmus, the great northern European humanist, compared Silenus to Christ and to Socrates in that all three seem unprepossessing but are in reality wise.

This Silenus, with his huge stomach and boozy hangers-on, is a classical translation of popular images of Carnival. Bruegel's painting The Fight Between Carnival and Lent personifies Carnival as a fat man riding a barrel of liquor, tilting at skinny Lent. Shakespeare's Falstaff is another fat leader of drunken sots who, as Prince Hal taunts him, lives in a permanent festive time: "Unless hours were cups of sack, and minutes capons, and clocks the tongues of bawds ... I see no reason why thou shouldst be so superfluous to demand the time of day."

Distinguishing features: The fat, flowing flesh of Silenus is the star of this painting. Looking like a naked Father Christmas, his white beard and hair topped off with vine leaves, Silenus is an unexpectedly graceful figure. His folds of fat are prodigious and move in a serpentine way; his chest is a colossally wide, sagging tower that the satyrs struggle to keep upright. His wine-reddened face is small, semi-bestial, but also might be that of a philosopher, with its white hair. His eyes are lost to sense; he barely knows where he is as he flows across the painting, a drunken wave.

Silenus's pubic hair draws attention to his flaccid state; not even the satyr who is supporting him - satyrs being incarnations of lust - has an erection. Drunkenness is depicted as a state of collapse, of loss of function, the yielding sack of Silenus's soft body.

Around him are images of natural abundance: purple grapes, fields, trees. Nature provides wine and it is natural, in this painting, to celebrate it.

Inspirations and influences: Homer Simpson.

Where is it? National Gallery, London