The San Marco Altarpiece is known as one of the best early Renaissance paintings for its employment of metaphor and perspective, trompe-l'œil, and the intertwining of Dominican religious themes and symbols with contemporary, political messages.

The Medici patron saints were prominently included in the dedication to insist to the friars that Cosimo and his wealth played a vital role in the convent's establishment.

[2] After acquiring the patronage rights to the choir and high altar in 1438, the Medici brothers executed their plans to replace the existing altarpiece by Lorenzo di Niccolò with one of their own.

[3] Cosimo de' Medici commissioned a friar in the Dominican community by the name of Fra Angelico to paint the new altarpiece, as well as additional frescoes in the cells, corridors, and cloister of the rebuilt monastery.

[3][6] The Medici's reign over San Marco and Cosimo's patronage were not just expressions of the Dominican Observance, but a foothold for political development as well.

The San Marco Altarpiece depicts a portrait of the Virgin and Child seated on a throne surrounded by saints and angels.

The formal elements are innovative for a contemporary Virgin and Child altarpiece as the positioning of the characters creates a deeply receding and logical space in front of the landscape background.

The pomegranate embroidered curtain behind the Virgin and Child establishes a distinct horizontal line separating the events depicted in the painting from the landscape behind it.

[3] While partially covered by the saints and angels, there is a definite line created by the carpet's receding squares in the foreground adding depth to the painting.

[10] The Virgin and Child are featured precisely at the vertical and horizontal axes' intersecting points and are placed above Angelico's trompe-l'œil depiction of the crucifixion.

Though they are sitting on a pedestal, the Virgin and Child do not seem much larger than the rest of the characters, showing a lack of a scale setting the main subjects apart from other mortals.

While he does create a sense of depth, the distance to approach the throne is minimal, which some historians perceive as a lack of awe for the holy figures.

One should also note that the San Marco Altarpiece is one of the earliest examples of sacra conversazione (sacred conversation), a type of image showing the Virgin and Child amongst saints in a unified space and single pictorial field, rather than setting them completely apart.

[10] The fictive curtains in the upper corners of the painting for example, signal alterity (or otherness) of the scene by drawing attention to the surface.

[2] The crucifix remained a fundamental component to the altar's furnishings as it represented the closest parallel to the action of Mass and the consecration of the body and blood of Christ.

The San Marco Altarpiece's crucifixion pax's gold background, archaistic figure, and almost gilded frame makes it clear that it is supposed to be seen as a separate painting.

The fact that it enhances the naturalism of the work behind it because of its appearance as another painting, not an actual part of the scene, makes it a perfect example of trompe-l'œil.

The crucifixion pax may also allude to a connection between Saints Cosmas and Damian as they too were condemned to the cross, as shown at the right end of the predella strip.

In the back, velvet-soft hills ring the shore of a wide placid sea stretching beneath a cloud-filled sky to the horizon, just above the Virgin Mary and Child.

Jesus's right hand, as seen in many other religious works, blesses all who aim their prayers and attention towards him, members of the choir included; it signifies his authority.

The rich, elegant Anatolian carpet embellishing the royal enclosure bears the yellow border marked around by the red Medici palle.

Just as the deacon and subdeacon knelt while helping the Dominican priest during Mass,[10] Saints Cosmas and Damian kneel in this altarpiece.

Angelico incorporates this religious practice through the vertically directed pax of the crucified Christ in the center to lead the viewer's eyes to Mary holding Jesus.

Saint Thomas Aquinas, one of the greatest Dominicans to have lived, composed the Latin phrase Contemplata Aliis Tradere, which translates as "To pass on to others the things contemplated.

Saint Mark turns the strictly theological and liturgical aspects of the altarpiece ("things contemplated") towards their end in preaching ("passing it on to others").

[8] There are still minor traces of cast shadows towards the bottom edges of the draperies in the painting, which are indicative of how Angelico gave the medieval equation of earthly and heavenly beauty new immediacy by translating it into the rational language of a representational style.

In addition, as Angelico implies in other ways, glazing was a technique used to create yet another boundary between the real world and the pictorial illusion.