This Belgian commemorative stamp from 1991 marks the 100th anniversary of Rerum Novarum, the influential 1891 papal encyclical addressing workers’ rights and social justice. The design features a modern, three-panel layout in green, red, and violet, symbolizing the evolving interpretation of Catholic social teaching across a century. The coat of arms near the top left reinforces the ecclesiastical theme. Issued at 14 francs, it is a sought-after modern Belgian thematic item for collectors of religion, social history, and anniversary issues. Clean typography and bold colors make it especially appealing in mint condition.