The term Chiaroscuro , while perhaps more ancient in concept, appropriately came into modern usage with the beginnings of the age of enlightenment. Out of the bigotted, prejudiced and religous, dark- and middle-ages, forward thinking people such as Leonardo da Vinci and Galileo began to explore the related and sophisticated concepts of art and science. The bright light of knowledge began to forge it's way through the dark and forbidding superstitous minds which belonged to the history of mankind.
One of the many themes which were specifically explored during this time was the curious effect of placing light and dark areas close together. The effect was to actually increase the sense of contrast between the objects, and to exagerate the unique qualties of each at the same time. The effect is called Chiaroscuro and can be seen in many circumstances. Perhaps one of the more exciting contexts is one where naked people are juxtaposed with clothed people. The one offsetting and balancing the other at the same time. Naturally, we being creatures of habit and prejudice, the tendency for us to crowd with others of similar mind is strong, and thus we see clothed groups and naked groups who do not generally mingle. When they do, however, the result can be bright and honest, as well as perhaps a little scintilating.