Panofsky separated identifying a figure holding a knife as Saint Bartholomew from asking why this patron wanted him on this wall. What does the second question require that the first does not?

C. Knowledge outside the picture: who paid, for what setting

A symbol dictionary names the figure and cannot say why a patron in 1590 wanted a flayed martyr over his tomb, that needs the contract, the chapel and the argument the image was joining. Stopping at identification is the standard failure, and it turns a document of a conflict into a label.