All Saints in an Initial E or O

This cutting may have been part of a lost set of choirbooks decorated by the Osservanza Master for the Church of Sant'Agostino in Siena. The initial E, excised from an antiphonary, introduces one of the responses for the Feast of All Saints (November 1): "Exultent justi in conspectu Dei" (Let the just exult before God). Inside the initial, painted to resemble an architectural interior, is the Virgin in prayer, surrounded by Saints. Standing next to her in the foreground are Saint Augustine on the left, and Saint Paul on the right. Partly visible behind them are the heads and gold haloes of numerous other saints.
The close stylistic affinities between works attributed to the enigmatic Osservanza Master and another Sienese master, Sano di Pietro, may indicate that they represent a single artistic identity. It is also possible that the works attributed to the Osservanza Master are the product of a collaborative workshop to which these artists belonged.