Tintoretto, Doge Nicoḷ da Ponte Invokes the Protection of the Virgin
Ducal Palace, Venice
The Doge's prayer may have to do with the great plague of 1575-1577, which took one third of the population of Venice. Da Ponte became Doge the following year, in 1578.
In the left half of the painting St. Anthony Abbot (tau-shaped staff, bell, tau on mantle) intercedes with the Virgin and Child on the Doge's behalf. The staff held by the character in the lower left could identify St. Joseph, though that saint's staff usually has flowers. It could be St. Christopher, who always has a staff in western art, though usually the Christ Child is on his shoulders.
The saint above the Doge is most likely Mark, the patron saint of Venice, with his Gospel book in hand. The saint on the far right is the Doge's namesake, St. Nicholas. (Note the three gold balls below his right hand.) This saint's role as protector of sailors at sea is referenced in his posture in this painting – with his shins up as if he were floating in on air. This is how he appears in many images of his coming to the rescue of imperiled ships (example).
More of St. Anthony Abbot
More of St. Joseph
More of St. Nicholas
More of St. Mark
More of the Virgin and Child
This image in full resolution
Photographed at the palace by Richard Stracke, shared under Attribution-NonCommercial-ShareAlike license.