Themes in Italian Renaissance painting

This article about the development of themes in Italian Renaissance painting is an extension to the article Italian Renaissance painting, for which it provides additional pictures with commentary. The works encompassed are from Giotto in the early 14th century to Michelangelo's "Last Judgement" of the 1530s.
The themes that preoccupied painters of the Italian Renaissance were those of both subject matter and execution – what was painted and the style in which it was painted. The artist had far more freedom of both subject and style than did a Medieval painter. Certain characteristic elements of Renaissance painting evolved a great deal during the period. These include perspective, both in terms of how it was achieved and the effect to which it was applied, and realism, particularly in the depiction of humanity, either as symbolic, portrait or narrative element.
Themes.
The "Flagellation of Christ" by Piero Della Francesca (above) demonstrates in a single small work many of the themes of Italian Renaissance painting, both in terms of compositional elements and subject matter. Immediately apparent is Piero's mastery of perspective and light. The architectural elements, including the tiled floor which becomes more complex around the central action, combine to create two spaces. The inner space is lit by an unseen light source to which Jesus looks. Its exact location can be pinpointed mathematically by an analysis of the diffusion and the angle of the shadows on the coffered ceiling. The three figures who are standing outside are lit from a different angle, from both daylight and light reflected from the pavement and buildings.
The religious theme is tied to the present. The ruler is a portrait of the visiting Emperor of Byzantium. Flagellation is also called "scourging". The term "scourge" was applied to the plague. Outside stand three men representing those who buried the body of Christ. The two older, Nicodemus and Joseph of Arimathaea, are believed to be portraits of men who recently lost their sons, one of them to plague. The third man is the young disciple John, and is perhaps a portrait of one of the sons, or else represent both of them in a single idealized figure, coinciding with the manner in which Piero painted angels.
Elements of Renaissance painting.
Renaissance painting differed from the painting of the Late Medieval period in its emphasis upon the close observation of nature, particularly with regards to human anatomy, and the application of scientific principles to the use of perspective and light.
Linear perspective.
Primarily through architecture, Renaissance artists were able to practice the art of three-dimensional illusion using linear perspective, which gave their works a greater sense of depth. The pictures in the gallery below show the development of linear perspective in buildings and cityscapes. 
Landscape.
The depiction of landscape was encouraged by the development of linear perspective and the inclusion of detailed landscapes in the background of many Early Netherlandish paintings of the 15th century. Also through this influence came an awareness of atmospheric perspective and the observation of the way distant things are affected by light. 
Light.
Light and shade exist in a painting in two forms. Tone is simply the lightness and darkness of areas of a picture, graded from white to black. Tonal arrangement is a very significant feature of some paintings. Chiaroscuro is the modelling of apparent surfaces within a picture by the suggestion of light and shadow. While tone was an important feature of paintings of the Medieval period, chiaroscuro was not. It became increasingly important to painters of the 15th century, transforming the depiction of three-dimensional space.
Anatomy.
While remaining largely dependent upon topographic observation, the knowledge of anatomy was advanced by Leonardo da Vinci's meticulous dissection of 30 corpses. Leonardo, among others, impressed upon students the necessity of the close observation of life and made the drawing of live models an essential part of a student's formal study of the art of painting. 
Realism.
The observation of nature meant that set forms and symbolic gestures which in Medieval art, and particularly the Byzantine style prevalent in much of Italy, were used to convey meaning, were replaced by the representation of human emotion as displayed by a range of individuals. 
Figure composition.
Among the preoccupations of artists commissioned to do large works with multiple figures were how to make the subject, usually narrative, easily read by the viewer, natural in appearance and well composed within the picture space. 
Major works.
Altarpieces.
Through the Renaissance period, the large altarpiece had a unique status as a commission. An altarpiece was destined to become a focal point, not only visually in the religious building it occupied, but also in the devotions of the worshippers. Leonardo da Vinci's "Madonna of the Rocks", now in the National Gallery, London but previously in a chapel in Milan, is one of many images that was used in the petitioning of the Blessed Virgin Mary against plague. The significance of these images to those who commissioned them, who worshipped in their location, and who created them is lost when they are viewed in an art gallery.
Fresco cycles.
The largest, most time-consuming paid work that an artist could do was a scheme of frescoes for a church, private palace or commune building. Of these, the largest unified scheme in Italy which remains more-or-less intact is that created by a number of different artists at the end of the Medieval period at the Basilica of St. Francis of Assisi. It was followed by Giotto's Proto-Renaissance scheme at Padua and many others ranging from Benozzo Gozzoli's Magi Chapel for the Medici to Michelangelo's supreme accomplishment for Pope Julius II at the Sistine Chapel. 
Subjects.
Devotional images of the Madonna and Child were produced in very large numbers, often for private clients. Scenes of the Life of Christ, the Life of the Virgin, or Lives of the Saints were also made in large numbers for churches, particularly scenes associated with the Nativity and the Passion of Jesus. The Last Supper was commonly depicted in religious refectories.
During the Renaissance an increasing number of patrons had their likeness committed to posterity in paint. For this reason there exists a great number of Renaissance portraits for whom the name of the sitter is unknown. Wealthy private patrons commissioned artworks as decoration for their homes, of increasingly secular subject matter.
Devotional paintings.
The Madonna.
These small intimate pictures, which are now nearly all in museums, were most often done for private ownership, but might occasionally grace a small altar in a chapel.
Secular paintings.
Portraits.
During the latter half of the 15th century, there was a proliferation of portraits. Although the subjects of some of them were later remembered for their achievements or their noble lineage, the identities of many have been lost and that of even the most famous portrait of all time, Leonardo da Vinci's "Mona Lisa", is open to speculation and controversy.
The nude.
These four famous paintings demonstrate the advent and acceptance of the nude as a subject for the artist in its own right. 
Classical mythology.
Paintings of classical mythology were invariably done for the important salons in the houses of private patrons. Botticelli's most famous works are for the Medici, Raphael painted "Galatea" for Agostino Chigi and Bellini's "Feast of the Gods" was, with several works by Titian, in the home of Alfonso I d'Este