Sometimes artists push their dealer too far, as a corker of a letter from Curt Valentin to Hans (Jean) Arp reveals. Sent after Valentin had laid the foundation for the artist-poet’s post-war success Stateside, the exasperated dealer wrote on 14 February 1951: “Dear Arpshole, thank you for your unpleasant letter of the 11th of this month. The fact that you have not received your money, mon cher, is down to your own revolting slovenliness.” Valentin did have a point, writes Eric Robertson, an Arp expert and professor at Royal Holloway College, University of London, who quotes the missive in his chapter in a book on Arp and the US recently published by the Berlin-based Arp estate. Valentin and Arp remained friends and business associates notwithstanding this Valentine Day’s contretemps, Robertson reveals.