The fascinating thing, is not to show the source of light, but the effect of light.
Nothing in art should seem accidental, not even movement
Make a drawing. Start it all over again, trace it. Start it and trace it again.
The frame is the reward of the artist.
It's easy to have talent at 20 but what is difficult is to have talent at 50.
Work a great deal at evening effects, lamplight, candlelight, etc. The intriguing thing is not to show the source of the light but the effect of the lighting.