One can’t seem to give a paper at a conference about coin designs without someone asking, if they’re really any more meaningful than a modern postage stamp [usually in a really special tone of voice]. Because of this ever present question and the resulting need to justify oneself, an apologetic reference to the metaphor is found in most modern books on ancient coin types (examples here and here and here).
The old trope comes from a 1950s debate between Jones and Sutherland. Jones in Essays Mattingly 1956 and Sutherland’s rebuttal in the widely read 1959 JRS article. [The latter some kind soul has put up on the web.]
Here’s the thing that gets me. Who are coin geeks to disparage stamps?!?! You’ve got to be kidding me that academics and enthusiasts alike can’t see the problem with this analogy as a negative analogy. There is good, fascinating work out there about the importance of stamp imagery as a vehicle for studying national identity, social norms, cultural trends over time… Why aren’t we reading this work?
Here’s a good place to start: