This panel is from an important five-part portable altarpiece that was possibly commissioned by the governing body of the city of Siena. Together with Giotto, Simone was the most famous artist of his day. His refined technique and descriptive powers, evident in the expression of Saint Andrew and the manner in which he holds his book, were unequalled in Europe and earned the praise and friendship of the poet Petrarch (1304–1374). The rectangular frame is original.