Giovanni Battista Tiepolo, 'Four Saints', before 1737

This oil sketch or modello shows the design for an altarpiece that Giovanni Battista Tiepolo made for the church of San Salvatore in Venice in 1737. It is now all that is left of the commission as the altarpiece was destroyed during the eighteenth century.

The painting unites saints who lived at different times and in different places. Seated on a throne above the others figures is Saint Augustine, an influential theologian and Bishop of Hippo, who lived from 354 to 430. He holds a flaming heart to symbolise his love for God. On the right, Saint John the Evangelist, who authored one of the Gospels, sits with an eagle, his symbol. Saint Louis – Louis IX, King of France – appears on the left. He fought in the Crusades, a series of wars waged between Christian and Muslim forces over centuries for control of the Holy Land and died while on campaign in 1270. We don't know who the bishop in a golden robe is meant to be, but all of these saints would have been important to the Cornaro family, the Venetian nobles who commissioned the altarpiece. This unknown figure is accompanied by two page boys, one holding a large book, perhaps the Bible, and the other a bishop’s staff.

Tiepolo used this compositional arrangement several times, as you can see from other examples of his sketches in the National Gallery’s collection: A Vision of the Trinity appearing to Pope Saint Clement and Saints Maximus and Oswald. Placing the figures against a loggia (open-sided gallery or room) or arcade like this one immediately establishes the scale of the scene. The architecture within the painting frames the action and replicates what the altarpiece would have looked like within the church, so the figures are directly related both to their surroundings and to the viewer in the real space in front of the altar. Their pyramid-shaped arrangement leads the eye from the lower saints to Augustine at the top.

An oil sketch like this would have been used by Tiepolo to show his patrons what a finished altarpiece would look like. Loose and energetic brushstrokes give the scene a rich, decorative texture, as do the touches of bold colour used to evoke sumptuous fabrics and delicate details, such as in Saint Augustine’s embroidered robe and Saint John’s rich red drapery.

Tiepolo’s son, Domenico, produced his own sketch of this composition (York Art Gallery), altering the placement and the poses of the figures in a number of ways. Of particular interest is Saint Augustine, who stands rather than sits and looks directly towards us, his arm outstretched above him with the flaming heart in his hand.