Focus on San Cassiano Altarpiece and discuss the History.
It is unknown when it was disassembled or why, but it was already in fragments when parts of it were documented by David Teniers the Younger for his Theatrum Pictorium in 1660. It wasn't until 1929 that three of the fragments were reunited by the Hungarian art historian Johannes Wilde. Other surviving fragments have been analysed to fit according to the model of a reconstruction in a virtual architectural study. Originally a larger altarpiece, it now comprises only the central panel with the Virgin Enthroned, and four half-busts of saints: St. Nicholas of Bari, Mary Magdalene (or Ursula), St. Lucy and St. Dominic.
Allegedly inspired by another Holy Conversation by Giovanni Bellini in the church of San Giovanni e Paolo (now known only through copies), it features however a more balance composition and a more sober architecture. Antonello adopted a pyramidal layout, enhanced by the accurate use of  light.
The book with three golden balls held by St. Nicholas alludes to the episode in which he gave them to three girls to be used as dowry.
Giovanni Bellini Mary Magdalene David Teniers the Younger Theatrum Pictorium Johannes Wilde San Giovanni e Paolo