Lord Lee of Fareham was one of the most remarkable philanthropists of the early twentieth century. As well as bequeathing his country estate, Chequers, to the nation, he conceived England’s very first university department for the study of art history and persuaded his close friend, the textile millionaire Samuel Courtauld, to bankroll it. Not only was Lee the driving force behind the foundation of the Courtauld, he donated his own art collection to the fledgling institute, helping to establish one of the world’s most richly endowed university galleries.

Among the treasures of the Lee Bequest were two ornate Renaissance wedding chests, commissioned by the Florentine merchant Lorenzo Morelli on the occasion of his marriage in 1472 to Vaggia Nerli. The only Renaissance chests of this kind to survive, intact, with their elaborately decorated spalliere, or backboards, they are currently the focus of a small but fascinating exhibition at the Courtauld Gallery, “Love and Marriage in Renaissance Florence”.

Fashioned by the carpenter Zanobi di Domenico, gilded by Jacopo del Sellaio, and decorated with narratives of early Rome by Biagio da Antonio, these objects occupy a middle ground between furniture, sculpture and painting. They are rare survivals from the so-called “Golden Age” of Renaissance Florence – the era of Lorenzo the Magnificent, when Botticelli was reaching his maturity and the young Leonardo da Vinci was taking his first steps towards greatness. Strictly speaking, they belong to the realm of domestic life, rather than that of declamatory, public art. But they are no less engrossing for that.

Marriage between members of the Florentine elite was a solemn and sigificant occasion. It was through marriage that dynasties were secured, alliances were formed and power was acquired. The most significant item commissioned for the home of the new couple was, traditionally, a pair of marriage chests, intended to occupy the camera of the bridegroom – the room where the husband would sleep and, it was to be hoped, fruitfully procreate with his new bride.

Such chests originally served the practical function of laundry cupboards. As the Renaissance humanist Leonbattista Alberti wrote, in his Treatise on the Family, they were meant for the storage of dresses and textiles (and most definitely not for oil and chickens, he added for the benefit of less well-bred readers). But their symbolic functions were more important. They were splendidly decorative objects intended to shed reflected magnificence on their owners. They were also intended to bring both good luck and sound morals to the household through the illustration of edifying stories from classical or modern sources. Scenes from Ovid or Boccaccio were equally likely to be depicted, with a strong emphasis on such male virtues as strength and fortitude, and such female qualities as constancy. Allegory is all. So it is that the decorative elements on the spalliere of the Courtauld chests include split pomegranates spilling their seeds, amounting to a kind of symbolic prayer for fertile married union.

Fifteenth-century Florentines saw themselves as the direct heirs of the heroes and heroines of Republican Rome, from which their own, nominally republican city-state claimed descent. On death, their bodies were often placed in especially commissioned Christian-classical sarcophagi (numerous examples are to be found among the wall tombs of a Florentine church such as Santa Croce). So it is perhaps no surprise that they chose a similar, classically inspired form to mark the solemn rite of passage to married life. The Courtauld’s immaculately preserved Morelli and Nerli chests are indeed very much a like coloured Roman sarcophagi, embellished with painting rather than bas-relief sculpture.

For all the splendour of the wedding chests’ intricately wrought giltwood forms, these pictures were meant to be the principal focus of attention. In this case, the stories intended for the contemplation of the new bride and groom were drawn from Livy’s tales of the heroic deeds of Marcus Furius Camillus. Painted in carefully calculated perspective, full of the fresh air and the bright, springtime colours of quattrocento Florentine painting, these comic-strip narratives are full of charm and circumstantial detail. In one of the scenes, ancient Romans in distinctly modern, Florentine dress play out the edifying tale of a duplicitous schoolteacher punished for his evil ways. In the other, wicked Gauls attempt to trick the Romans into paying them an inflated tribute of gold by using false weights and measures. What greater sin could there be, in the eyes of a Florentine merchant? But all is well and order is restored, as the hero puts these traders in perfidy to the sword. The action takes place in a dry, Tuscan landscape, dotted will hilltop towns.

When Giorgio Vasari published the second edition of his Lives of the Artists, in 1568, he included a whole section on paintings made for the front of cassoni, or wedding chests. By his time, the practice of painting elaborate narrative and allegorical scenes on such items of domestic furniture had come to seem rather old-fashioned – and he wrote about it as if it were already a rather quaint tradition from a less sophisticated past. “The stories which they made on the front,” he wrote, “were for the most part tales taken from Ovid and other poets ... and also hunts, jousts, novelle of love, and other similar things, according to what each one liked best.”

But Vasari neglected to add something rather important - namely, that it was from the apparently slight and light-hearted tradition of cassone painting that one of the most vivid and vital traditions of Western European narrative art would subsequently evolve. Botticelli’s monumental Birth of Venus and Primavera are rightly regarded as among the first pure mythologies in Renaissance art. Yet both were painted to celebrate Florentine marriages – and therefore were, in effect, cassone paintings freed from the tradition of the wedding-chest itself. From those pictures, in turn, descends the whole tradition of post-Renaissance mythological art – the mythologies of Mantegna and Titian and Raphael, of Rubens and Poussin and countless other masters. So the Morelli-Nerli chests are not only the most perfectly preserved examples of a long since defunct art form. Each one is a Pandora’s Box, from which all kinds of other dreams took flight.