In Van der Weyden’s version (the best by anyone), Luke is drawing with a stylus, so he’s unencumbered by painting paraphernalia. What he’s doing is very focused, very direct.

Rogier van der Weyden (1400-64) was an outstanding master of the new technique. As official painter to the city of Brussels, he achieved international fame and a considerable fortune.

An altarpiece loaded with symbols that point all the way back to Adam and look forward to the Resurrection. ... scholar Walter Friedländer characterized Rogier van der Weyden (c. 1400-1464/65) ...

The painter was a Flemish master, Rogier Van Der Weyden. Today it is one of the greatest masterpieces in Spain's National Gallery, the Prado, in Madrid.