The bas-reliefs on this marble slab are attributed to Gano di Fazio. They tell of certain miracles in the life of Joachim "Piccolomini". Born in 1258, at the age of 13 he entered the Servite Convent in Siena, a mendicant order whose piety was centred on the cult of the Virgin. This congregation was a recent creation, having been founded only in 1233. Joachim's exemplary life and his posthumous miracles would spread his order's fame. In the wake of St Francis of Assisi, he was a contemporary spiritual example whose proximity aroused an accessible and popular devotion. Joachim was beatified in 1609 and rose to the rank of blessed but was never canonised and therefore never officially considered a saint by the Church. However, to proclaim his cause and that of his order, he is shown with a halo around his head, a sign of his sainthood, as claimed by the Servites.

These bas-reliefs were part of the funerary monument of Joachim "Piccolomini" in the Servite Basilica of Siena. The monument was probably carved after 1310, when the monks decided to celebrate his life, once the first miracles were documented.

Inspired by the narrative trend in contemporary painting, these scenes are worked in a particularly vivid style and resume the tripartite arrangement in the manner of an altarpiece predella. The first episode, to the left, depicts the entrance to the convent, whose door opens itself to the future Servite. The last two scenes portray miracles connected with the epilepsy from which Joachim suffered. In the central episode, he is shown striking a table in mid-seizure without spilling or breaking anything. The depiction of the dishes and food provides an opportunity for a still life which testifies to the quest for realism in the Gothic style. In the final part, on the right, a candle burns without being consumed during the Eucharistic elevation while Joachim collapses in the throes of a new seizure.

The understated style of this work turns its back on the complexities and elegance of Gothic sculpture in northern Europe. The frontal nature of the layout, the dynamism and the clear definition of the characters create an effective narrative. With even greater clarity, the classic style of Gano di Fazio perpetuates the quest of Nicolas Pisano, who worked on the pulpit of Siena Cathedral circa 1265, and of his pupil, Arnolfo di Cambio.