Begin by painting your shadows light. Guard against bringing white into them; it is the poison of the picture, except in the lights. Once white has dulled the transparency and golden warmth of your shadows, your color is no longer luminous but matte and gray.
-attributed to Rubens –
Dark is the basic tone of Rembrandt’s paintings, and darkness occupies a large area in them…. But how full of life is such darkness! Beginning with the most glowing middle tones of brown and yellow, they are gradually deepened through glazes and accents and made so unutterably rich in values!”
-Max Doerner (1949), The Materials of the Artist