Aristotle with a Bust of Homer, Rembrandt (1653)

Artist: Rembrandt van Rijn (1606-1669) is such a universal artist that we tend not to place him in a school or fashion, but the movement that makes most sense of his themes and radical innovations is the Baroque - the theatrical, emotive art and architecture that swept Europe in the 17th century. Rembrandt, born in Leiden but from 1632 onwards dominating the art world of Amsterdam, rejected the patient naturalism of Dutch art for a dramatic juxtaposition of portraiture and history, reality and myth, that is a one-man Dutch Baroque. His paintings of goddesses such as Flora and Juno are real women dressed up as the classical deities, giving mythology a pathos.

Subject: Aristotle, ancient Greek philosopher, contemplates a bust of Homer, archaic poet, notional author of the Iliad and Odyssey.

Distinguishing features: Homer is blind, his eyes brown voids that lead the eye into an inner darkness. The sightless eyes of Homer's bust, on which Aristotle rests his hand, are innocent and profound; Homer's face is humble and weak, and he wears a simple shift. The gold light catches his head and illuminates the face of Aristotle, whose black eyes look wanly - knowing too much - at Homer. This is a painting partly about the uses of portraits.

In his Renaissance treatise On Painting (1435), Leon Battista Alberti argued that one of the uses of art is to preserve the images of the dead so that they can be looked at many years later. Alberti used the example of a portrait of Aristotle's pupil, Alexander the Great, which, after Alexander's death, brought one of his generals to tears. The Renaissance cult of the portrait was aware of portraiture as a historical document. The portraits that survived from the ancient world were primarily busts, and that is what Rembrandt depicts here.

This is doubly nostalgic: Aristotle, who lived in the fourth century BC, meditates on a portrait bust of Homer, a legendary figure from three centuries earlier. So Aristotle contemplates a portrait that is a token of a remote past, and we contemplate both that and the painted portrait of Aristotle as Rembrandt imagines him. Homer's image in ancient statuary is conventionalised, and Rembrandt acknowledges that any portrait is to some degree a fiction. And yet, because of Rembrandt's brilliance, we find it hard to dismiss Aristotle as a figment of paint. It seems to be the real man before us, really thinking. Other artists give us the appearance of their subjects; Rembrandt conveys interior life, a consciousness.

The deep chiaroscuro, the face of Aristotle emerging, gold-licked, from darkness, the eyes so weighted with emotion, makes us feel time has collapsed and that we are communing directly with Aristotle as he communes with Homer. Rembrandt, in his late 40s when he painted this, contemplates the age of the world. The centuries weigh on us, as that gold chain with its presumed portrait of Alexander weighs on Aristotle. You could interpret this painting as a morality tale - that Aristotle, the successful, well-dressed courtier, envies Homer, the blind but free artist; or that science defers to art. But whatever interpretations are made and unmade, this painting will remain one of the greatest and most mysterious in the world, ensnaring us in its musty, glowing, pitch-black, terrible knowledge of time.

Inspirations and influences: This painting, commissioned by Rembrandt's Sicilian patron, Don Antonio Ruffo, had a documented impact on Italian art: the Baroque painter Guercino made a pendant, now lost, on which he praised Rembrandt as "a great artist".

Where is it? Metropolitan Museum of Art, New York.

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