The Principle of Interchange

In the 19th century many scholars studied the Renaissance to learn painters’ secrets, techniques and principles. Notable among them were Sir Charles Eastlake with his book on the “Methods and materials of Painting of the Great Schools and Masters” first published in 1847 (but available today by Dover Publications) and also in the mid 19th century there is the prolific John Ruskin with his ” Elements of Drawing” and his “Elements of Perspective,” among many other books.  (“Elements of Drawing” is today published by Dover.) In this book Ruskin tried to reconstitute many of the organizing principles of  Renaissance painting. One of those was the principle of  interchange.  This principle explained that an object might change its color or value identity to contrast with changes in background.

Look at Monet’s Poplar trees (above). Observe that in circle 3 the background contrast is a dark bank while the tree is a lighter lavender but as the trunk rises up it becomes bluer and darker (circle 2)  against the lighter yellow/orange background trees and, as the same trunk rises up still further into the blue sky it becomes orange (circle 1) – the opposite of  the complementary color of the sky which now surrounds it.  The trunk has changed its color and value  to contrast with the different background changes. This action illustrates the principle of interchange with complementary colors. In my painting I am not trying to create the same complementary harmony (or contrast through colors that are opposites on the color wheel) as Monet did but rather, I created areas of analogous harmony (colors that are adjacent on the color wheel).  Observe that my amber and orange trunks also transition into other colors and values but, in my painting, I have them transition with the background. In either Monet’s example or mine we are both using the principle of  interchange.