Otto Fischer - Kunst-Anstalt für Moderne Plakate - Wilhelm Hoffmann, Dresden, 1896
The pattern
This still is filed under Demonstration ad.
Define
The product does the arguing. The viewer sees the thing work, not a slogan about the thing working.
Mechanism
Proof by performance. The claim is the action: a visible, testable result the reader can replay.
Verdict
We can show a result in seconds
Why it works
The product is not described, it is being consumed inside the frame - two absorbed faces tell the buyer what their own poster will do to a passer-by. The lettering is drawn, not set, and is fitted into the negative shapes left by the figures, which is itself the sample: it proves the firm can integrate type and image, the exact skill being sold. Reversing the foot line out of the black table mass keeps the firm's name at the same visual weight as the headline without adding a second type size.
Steal this when
Use it when you sell a craft service and your best argument is your own marketing - an agency, a printer, a studio. Show the work being used by a believable customer rather than displayed on a wall, and let the execution of the ad itself carry the competence claim.