Mathematics and art through the strings as with a bird cage and to see one form within another which excited me." The artists Theo van Doesburg and Piet Mondrian founded the De Stijl movement, which they wanted to "establish a visual vocabulary elementary geometrical forms comprehensible by all and adaptable to any discipline". Many of their artworks visibly consist of ruled squares and triangles, sometimes also with circles. De Stijl artists worked in painting, furniture, interior design and architecture. After the breakup of De Stijl, Van Doesburg founded the Avant-garde Art Concret movement, describing his 1929–1930 "Arithmetic Composition", a series of four black
Theo van de Klundert and History of Economics at Tilburg University. Among his doctoral students are Casper van Ewijk, Henk van Gemert, George Gelauff, Ad van de Gevel, Raymond Gradus (in cooperation with Piet Verheijen), Rob de Groof, Gustaaf Hes, Lex Meijdam, Richard Nahuis, Henk Peer, Eric Schaling (in cooperation with Sylvester Eijffinger), Sjak Smulders, Ton van Schaik, Herman Thoben and Jeroen van de Ven, Herman Wijffels. In 2001, Van de Klundert retired from Tilburg University. Since 1967, Van de Klundert has been associated with the scientific journal "De Economist", initially as editor, later on as chairman of the board of editors. Since 1976