All Reflected Colours are less vivid, and appear with less force, than those which receive their Light directly; the direct or incident Light, bearing the same Proportion to the Light reflected, which the Luminous Bodies occasioning them, bear to one another in brightness and Lustre. A Reflex proceeding from a Body more obscure than that which receives it, will be weak and almost insensible; on the contrary, where the Ground on which it is received, is darker than the Surface whence it proceeds, it will be bolder and more visible: Lastly, It will be still more sensible as the Ground is more obscure, and dimmer, as it is more bright.