Initially, Jaap ter Haar was only known as an author, including the well-known series of adventures by Saskia and Jeroen. After his 'History of the Low Countries', a book on which he worked for five years, Ter Haar had had enough of the 'toil' behind the typewriter. He started carpentry and painting furniture. He became so fascinated by paint that from then on he only devoted himself to painting. Landscapes and cityscapes were his favourite subjects. He was also inspired by events in his daily life in Hilversum and later Blaricum. Because of the consciously naive style that the painter uses, he belongs to the group of Dutch naive or Sunday painters.