Odilon Redon (1840-1916) was a member of the French Symbolist movement. The image the Two Trees (part of his noir series) uses tone to create both a way into the image with the lighter tone leading into the trees from the bottom right and a sense of foreboding with the very dark tone between the two tree trunks. You want to go up to the trees and peer up the path beyond without venturing into the space as you are fearful of what you might find. Tonal variations on the tree give a sense of the rounded form of the trunk and of the weight/solidity of the tree. The shading lines and spots provide texture to the tree and give a strong feeling of the roughness of the bark.
Other images include:
All the images use tone to both define the form and create a somewhat sinister, mystical atmosphere. This atmosphere is particularly created by the dark background tones with the face almost fading back into the picture and the dark tones around the eyes which add a sadness to the images. With the Temptation of Saint Anthony, even though the face is mainly in light tones, the background dark figure and odd bat-like wing adds a dark feeling to the image.
Up to now I have mainly thought of tone to create structure and form to the objects within my drawings, however, Redon shows have tone can also be used to give a dark (or light) atmosphere to a drawing and it is something that I will need to consider in the future.