French for "deceive the eye," trompe l'oeil is the painting technique where the artist makes an image that appears three dimensional and outside the painting. The concept goes back to Roman art, where walls in houses would have fake windows of iterms painted on, but was first defined in the Baroque era. The technique can be used to either enhance the dimensionality of a painting, or as a kind of artistic joke, featuring a "mistaken" element.

Each painting features a remarkable realism in its portrayal of the figures included therein, including a self portrait of the painter. Francisco de Goya likely included himself in his painting as a nod to Velázquez' own self-portrait in Las Meninas, with both standing behind an easel placed in the left side of the painting. Both painters include themselves to make the viewer rethink what they see in the painting of royalty, with the gaze of the painter staring back at the viewer.

Figure 1: Las Meninas by Diego Velázquez (1656)

Figure 2: Charles IV of Spain and His Family Francisco de Goya (1801)

Chiaroscuro is an artistic term denoting a strong contrast between dark and light elements. First developed and defined in Italy in the late sixteenth century, chiaroscuro was a key element of Rembrandt van Rijn's style. In The Night Watch, he throws significant light on the group's leaders exiting the hall, with shadow taking over those in the back.

Figure 3: The Night Watch by Rembrandt van Rijn (1642)

Figure 4: The Astronomer by Johannes Vermeer (1668)

The "Cavalier" dress refers to men with flowing ringlets, high leather boots, brightly colored fabrics, lace collars, and elaborate trimmings. The word "Cavalier" described the Royalist factions in the English Civil War (1642-1651), although Van Dyck painted portraits of Royalist and Parliamentarian leaders before the war. In fashionable portraiture over the next centuries, especially in England, "Cavalier" style was a popular way to be presented.

The most famous "triple portrait" is the one that Sir Anthony van Dyck painted of King Charles I of England in 1635 or 1636. The painting was supposed to be used as a model for a bust, and the three different angles of Charles' face were intended to allow for a possible three-dimensional model. The painting became widely copied in the next few centuries, as it not only showed off the subject but also exhibited the skill of the artist.

An orrery was an early form of planetarium, and it was meant to show how the planets move in the solar system.  The light projecting from the left side was meant to represent the sun.  The philosopher is demonstrating what happens during an eclipse in this image.

Image is in the public domain, accessed through Wikipedia Media Commons: https://en.wikipedia.org/wiki/File:Wright_of_Derby,_The_Orrery.jpg

Wright uses tenebrism in A Philosopher Giving a Lecture on the Orrery. Tenebrism is using very contrasting lights and darks, to the point that the the darkness dominates the image. This then emphasizes the light spots even further -- in this painting, the parts lit by candlelight are very noticeable in comparison to the rest of the image. Wright painted several "candlelight pictures," and he was influenced by Caravaggio, who also made use of tenebrism in many of his works.

Image is in the public domain, accessed through Wikipedia Media Commons: https://en.wikipedia.org/wiki/File:Wright_of_Derby,_The_Orrery.jpg

As a Rembrandt portrait, the most notable and identifiable quality of the painting is its chiaroscuro lighting, or its use of extreme light and shadow. Rembrandt was not known for visible brushstrokes or vivid colors, and neither are on display here. The textures are not especially unconventional, and in any case that fact and the use of an older subject are not immediate signifiers of Rembrandt's work.

Image is in the public domain, accessed through WikiArt: http://www.wikiart.org/en/rembrandt/old-man-with-turban