Group of progressive Belgian painters and sculptors (originally twenty in number, hence the name) who exhibited together from 1884 to 1893. The members included James Ensor and Jan Toorop. They showed not only their own work, but also paintings by non-Belgian artists such as Cézanne, van Gogh, and Seurat. The group was influential in spreading the ideas of Neo-Impressionism and Post-Impressionism and became the main Belgian forum for Symbolism and Art Nouveau. Although the group dissolved in 1893, its work was carried on by an association called La Libre Esthétique, which ran from 1894 to 1914. Most of the leading Belgian avant-garde artists of the period were members.