THE title of this essay is suggested by a passage in Geoffrey Chaucer’s poem Troilus and Criseyde. As a result of an exchange of prisoners, Criseyde has been transferred from Troy to the Greek camp. While still in Troy, she had promised her lover to return within ten days; but now she finds that the prospect frightens her, and she wishes that she had taken Troilus’s advice and stolen away from Troy in his company. She realises that she made a bad decision:

Prudence here looks in three directions: towards past time through memory, towards present time, and, with her third eye, towards future time. It is this third eye which, Criseyde now thinks, failed her when she agreed to go along with the exchange of prisoners.

The strange image of a head with three eyes (or sometimes with three faces), looking away at right angles from each other, appears elsewhere among the emblems of prudence, both in literature and in the visual arts. Two examples will suffice here. In Canto XXIX of the Purgatorio Dante, having arrived in the earthly paradise, sees a divine pageant which includes the four cardinal virtues ‘following the measure of one of them that had three eyes in her head’:

Thus Prudence leads the other three virtues – Temperance, Justice, and Fortitude – in their celebratory dance. Pictorial examples from the Middle Ages are not hard to find; but the most remarkable treatment of the subject is by Titian, in a painting known as ‘An Allegory of Prudence’, now in the National Gallery in London. This picture shows three human faces placed together above the faces of three animals. On the left, in shadow, is the face of an old man, above that of a wolf; in the middle, the faces of a man in his prime and a lion look straight out at the viewer; and on the right, the faces of a young man and a dog look away into the light.