Cosimo the Elder, Pontormo (c1516-20)

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Artist: Jacopo Carucci (1494- 1556) took his name from his birthplace, Pontorme, in Tuscany, but it was in Florence that he spent his life as an artist, remaining loyal to the politically and artistically explosive birthplace of the Renaissance, at a time when most artists of his ability made a beeline for Rome and papal patronage.

Pontormo was a disciple of Michelangelo, with whom he collaborated at the beginning of the 1530s, after the fall of the Florentine republic. Pontormo painted a Noli Me Tangere from the older man's drawing; the commission came from a general in the Imperial army, who had crushed the republic despite Michelangelo's defence of the city. Pontormo made his own contribution to the republican ideal with a painting, now in the Louvre, in which militia and public servants of Florence are protected by the Virgin and St Anne.

But most of all, he was a poetic painter, learning from Michelangelo to strain bodies and space in pursuit of eerie suggestiveness. Pontormo's masterpiece, The Deposition, in Santa Felicita, Florence, is a painting without weight, in which pale yet furious colours and bodies create a delirious, sensual, spiritual revelation.

Subject: Cosimo de' Medici (1389-1464), a brilliantly subtle politician, projected sensitivity in a way that disarmed resistance and established the charisma of the Medici. Cosimo, apparently tormented by the wealth of the Medici bank, had his own cell in the convent of San Marco, where he could retreat and contemplate TheAdoration of the Magi by Fra Angelico and Benozzo Gozzoli.

It was Cosimo's pious generosity that made the reputation of Medici magnificence, while his loans to citizens created a network of debt. When he died, the city voted to engrave over his tomb: "Pater Patriae", Father of his Country (Florence).

Distinguishing features: This posthumous portrait - Cosimo was dead nearly 60 years - meditates on history, memory and the nature of power. Cosimo is a startlingly unfearsome presence in this painting commissioned by the inheritors of his power. It is a painting that restates Renaissance traditions of official portraiture.

Cosimo is portrayed anachronistically - not according to the portrait conventions of Pontormo's time, but in profile, as a 15th century artist would have shown him. Profile portraiture in Renaissance Italy was an emulation of heroic profiles on ancient Roman coinage.

Yet Pontormo invests this image with the opposite of military might. Cosimo is an introspective Renaissance man, passionate and nervous, wringing his hands. But determination is there, too: a steel inside the soft glowing robes whose fire of red is Pontormo at his most poetic.

Next to the pensive Cosimo is an emblematic statement of Medici resilience. The green fresh growth sprouting despite raw, cut branches is the broncone, promoted in the 16th century as a symbol of the Medici's ability to keep coming back however many times they were thrown out or died. "As one is torn away another appears," declares the twisting white scroll.

This painting suggests sensitivity rather than rampant authority, a historical interpretation of Cosimo's power to suggest that the Medici govern Florence, if they must govern it, with the nuance and character of their great ancestor. This was a vain hope.

Inspirations and influences: This nostalgic image of Cosimo the Elder is contemporaneous with Raphael's far more brutal portrait of the Medici Pope Leo X (1518, Uffizi).

Where is it? Uffizi, Florence.