The term "tenebrism" refers to the use of large areas of very dark shadows in a painting, juxtaposed with other areas of very bright lighting. Caravaggio was probably one of the most glorious in his use of this melodramatic painting effect. It can be seen in his Calling of Matthew, his Conversion of St. Paul, and his Judith and Holofernes. In today's world of fluorescent, indirect lighting, it's easy to forget the effect of a single candle in a dark room and the impact it has on reflecting flesh tones or other objects. In the mid-1700s, over a hundred and fifty years after Caravaggio capitalised upon it, the effect was sort of "rediscovered," so to speak, by an English artist by the name of Joseph Wright.
You've probably never heard of him and that's understandable. He was an excellent academic painter, a member of the Royal Academy, but not a Gainsborough or Reynolds by any means. He was a skilled practitioner who happened to be as much interested in science as art; and found exciting ways to blend the two together. About 1765, for instance, he experimented with nocturnal light effects, using moonlight, painting several scenes he observed of Mount Vesuvius erupting. Later, he moved inside and depicted a number of scientific experiments. His work is a meeting of the arts and sciences that in fact, was not all that exceptional at the time, especially in the days before modern photography. Today unfortunately, it seems to us quite unusual.
Probably the best example of Wright's use of tenebrism and the melding together of art and science can be seen in his 1766 painting, A Philosopher Giving a Lecture on the Orrey. Okay, what's an Orrey? Even in seeing the painting you're not altogether sure what kind of contraption you're looking at. Basically it seems to be a miniature solar system utilising a candle at its centre to represent the sun and various brass or wooden rings to demonstrate the placement and movement of the known planets of the time. Besides the lecturer, seven other figures study intently the surprisingly complex educational device. Some seem to be scientists, others are students, women, and children, all leaning into the scene from the deep, tenebric shadows of the corners and edges of the painting. Like the work of Caravaggio and French artist, Georges de la Tour, who also employed tenebrism, the life-size painting is first of all eye-catching for its dramatic light, then intensely interesting for its curious, scientific content. It makes one wonder why science is not more often the subject of art today.