Looking through the Historical Archives of the Veneranda Fabbrica del Duomo di Milano, which preserve documents, scrolls, and mandates from the second half of the 14th century up to the present day, one unveils many interesting testaments to and stories about the lives of artists and painters whose paths have, over the years, intersected that of the Cathedral, the international symbol of Milan and a veritable treasure chest of art and religion.
In studying the Sant'Ambrogio altarpiece by Federico Barocci, the only canvas by the artist still in the Duomo di Milano, various interesting facts emerged regarding the artist and his works. The Milanese painting “S. Ambrose's forgiveness of Theodosius”, full of touching religious intimacy and poignant portraits, rich in detail, is considered one of the first authentic Baroque works of art, a concept that refers to the return to a certain pictorial and human quality which mannerism had, by then, nearly done away with in favour of mental finesse and academic detachment.
The altarpiece, situated among the later works of the Urbino period, represents the high point of Barocci's artistic evolution due to his unique articulation of the deeper space and the free and sloping arrangement of the characters in the scene, painted, for the most part, with raw and skilful technique, rife with energy and atmosphere.
Coeval with the Sant'Ambrogio altarpiece is the "Deposition", left unfinished by Barocci and destined for the altar of San Giovanni Buono in the southern sacristy of the Duomo di Milano, then transferred to private ownership in 1786 and today preserved in the picture gallery of the Archiginnasio of Bologna's library.
Regarding this piece specifically, many letters and mandates found among the Archives' documents made it possible to reconstruct the unusual events around its completion. In fact, in 1612 Barocci died and it was one of his disciples, Ventura Mazzi, who took on the task.
The painting, requested by the Veneranda Fabbrica del Duomo in the 17th century for the altar of San Giovanni Buono, was unfinished. Francesco Maria Cappuccino, in a letter dated 9 September 1629 and addressed to Cardinal Federico Borromeo, specifically indicated that Ventura Mazzi was to complete it, as he was "[Barocci's] first disciple and had his same manner" (Valsecchi, p. 230). In another letter to the Veneranda Fabbrica dated 19 April 1635, Mazzi affirmed that he would be able to finish the painting because he had "the same manner as my teacher, his drawings in order to complete the painting, and the small painting which will be needed to accommodate errors" and stated multiple times that he would have sent a draft of the work "the same as the large one, but finished; consistent with the vision and drawings left behind by Baroccio" (Arslan, pg. 35 n. 81; Sangiorgi, pg. 63 s.).
This letter is important evidence of the system adopted in the Barocci's studio: his students were accustomed to completing his paintings or creating copies, either through the use of original drawings by their teacher which reproduced particular details or the whole, or through the use of previous drafts. Mazzi was thus entrusted with the task of finishing the canvas. On 10 September 1635 he received a reimbursement of expenses for having shown Barocci's incomplete painting to the Fabbrica del Duomo the previous year: "The Chapter has instructed that you be compensated for the return trip to your town, having come last year to accompany the altarpiece begun by Federico Baroccio, painter of the altar of S. Giovanni Bono” (Arslan, pg. 107 n. 233).