Two Horses at a Halting-place, Rembrandt van Rijn, c. 1637
This study of two pack horses being fed and cared for gives the impression that they really were drawn on the spot. The motifs seem to have been depicted at lightning speed, almost without lifting the chalk from the paper. The head of the nearest horse was drawn first only in black chalk. Later Rembrandt worked it with a piece of red chalk, which he had sharpened into a very fine point.