St Catherine, enthroned, wears the black and white robes of the Dominican Order. The white lilies symbolise her purity and the fact she flattens the devil underfoot signals her goodness. St Lawrence and St Dominic are on the left and St Peter Martyr and St Raphael, with the young Tobias, to the right. St Catherine of Siena was the first Dominican nun and here she presents a book of the Dominican Rule to one kneeling group of figures and a scroll of regulations to another. The altarpiece may have been painted for St Catherine's convent, Florence, where three of Cosimo Rosselli's nieces were nuns.