Self-portrait with Curly Hair, Rembrandt van Rijn, c. 1630
Rembrandt was fascinated by the effects of light. This is also clear in his etchings, for instance in these diminutive self-portraits in which his face is mostly half cast in shadow. In the version with a fur cap, we can see that this head covering was added only at a later stage. He began the etching with a bare head: his hair is still visible through the cap.