Shown is the mural in the Abbey of Middelburg, painted in 1957 on a wall of 700 sqft (over 7 m wide and 9 m high). It is an allegorical representation of the taxation of agriculture, livestock and fisheries - payment in kind - in the province of Zeeland in earlier times.
The larger than life figures were drawn in the studio of the painter on tracing paper. His wife made templates using a tracing wheel for the purpose of transferring of the contour lines of the figures on the wall using chalk. Because of his fear of heights it took several days before Koolen dared to climb the ladders and scaffolding to paint the mural. See publication.
The mural is made on wall A. There were plans for wall B (with a large window, on the right) but not executed. See also the sketches below.