3. The Master of the Osservanza.
As readers will be aware, this is the terminology used in the history of figurative arts to assign to an artist who is anonymous, but who can be dated and identified on the basis of the features of his style, works of art which cannot be attributed by means of documents, or on the basis of other evidence, to artists whose names are known.
In 1940 a distinguished scholar, Roberto Longhi, stuck to his well-founded doubts over the traditional attribution of the Osservanza triptych to Sassetta, preferring an anonymous artist: His doubt originated from the date contained in the inscription which can easily be seen at the bottom of the painting: 1436. Our triptych, dated accordingly, seemed to be still overly linked to the Gothic-style taste of the late 14th century, and to ‘two-dimensionality’, to be dated four years later than Sassetta’s Madonna delle Nevi (now in the Uffizi gallery), in which one can already see certain 15th century innovations.
The nature of the doubt led Cesare Brandi to posit a youthful phase of the activity of Sano di Pietro, one not as yet documented, when the unknown Master was already being attributed a large and interesting series of works, as well as the Osservanza triptych and its predella (altar-step), currently in the public art gallery (Pinacoteca) in Siena: the Pieta with San Seboldo (now in Siena’s Monte dei Paschi bank); the eight panels of the story of Sant’Antonio Abate (scattered between museums in Berlin, New Haven, Washington and New York); the Nativity of the Virgin from the Collegiata in Asciano (now in the Museum of Sacred Art); the panels of the predella with Stories of the Passion (now split up, and located in the Vatican Galleries, as well as Philadelphia, Cambridge (Massachussets), and Detroit); a predella showing the Martyrdom of St Bartholomew (in the Pinacoteca in Siena); and the altar-piece showing St George and the Dragon (from the church of St Christopher, now in the museum of the Oratory of San Bernardino in Piazza San Francesco).
Very soon, what had been interpreted as a 14th century anachronism was seen as revealing the taste for purity of colour and for decorative motifs, typical of the work of the Sienese school which was moving in a wholly different direction compared to the Massaccio-inspired innovations. It was thus a more archaizing and more aristocratic pictorial art compared with the parallel output of Sano and Sassetta.
A new interpretation of the four letters ‘hcmc’ in the inscription below the Osservanza tripytch sees in it the formula of a will, to the extent that the date of 1436 can be considered as the year when the work was commissioned. The work can thus be dated to later years.
More recent hypotheses which have been formulated include the name of Francesco di Bartolomeo Alfei (known as an artist active in the 15th century, but who has no work atributed to him), and a workshop of several painters, in which Sano could also have worked, not necessarily in his youthful period.