Light and shadow
Light makes forms round, sets the mood and guides the eye. It is the painter’s most powerful storytelling device.
To give a form volume, the painter shows the light where it strikes, the shadow where it cannot reach and the transition between them. The Italians called this play of light and dark chiaroscuro.
Leonardo softened the transitions into sfumato, a smoky haze without sharp edges. Caravaggio went the other way: his figures emerge from pitch-black darkness into a hard, directed light – tenebrism. Rembrandt and Vermeer made light itself the subject, and the Impressionists chased it out of doors.