Contrast is a value concept that determines how much difference there is between the elements of high-key and low-key within a work. Some works, such as this one by Peter Paul Rubens have very little contrast. Others, like this painting by Albert Bierstadt have more contrast. Note that sculptures that are made from one medium tend to be monochromatic. This would suggest that there is little if any contrast, and yet, the use of actual light and shadow can be very effective in creating contrast, as in the Lincoln Memorial. Not all sculptures take advantage of that effect, but those that do can be quite dramatic.