In the 1960s, Wiskunde Post, a mathematical magazine for young people, played an important role in the promotion and dissemination of “modern mathematics” in Flanders. The initiative came from three enthusiastic mathematicians, Paul Bockstaele, Gaspard Bosteels and Roger Holvoet. The magazine covered topics in the history of mathematics, “traditional mathematics” and “modern mathematics”, but the latter topics in particular were completely new to most readers, not only students but also their mathematics teachers. Many of them were first introduced to the mathematics of sets, relations, algebraic structures and topology through Wiskunde Post. Motivation for or applications of the new mathematics were largely lacking, however; it was primarily the mathematics itself that was supposed to captivate the magazine’s readership.