The friendship between Van Doesburg and Mondrian remained strong in these years, although their primary way of communication was by letter. In 1923 Van Doesburg moved to Paris together with his later wife Nelly van Moorsel. Because the two men got to see each other on a much more regular basis the differences in character became apparent: Mondrian was an introvert, while van Doesburg was more flamboyant and extravagant. During 1924 the two men had disagreements, which eventually led to a (temporary) split in the same year. The exact reason for this split has been a point of contention among art historians; usually the divergent ideas about the directions of the lines in the paintings have been named as the primary reason: Mondrian never accepted diagonals, whereas Doesburg insisted on the diagonal's dynamic aspects, and indeed featured it in his art. Mondrian accepted some concepts of diagonals, such as in his "Lozenge" paintings, where the canvas was rotated 45 degrees, while still maintaining horizontal lines. In recent years, however, this theory gained critique from art historians such as Carel Blotkamp, who cites their different concepts about space and time as the main reason for the split. After the split, Van Doesburg launched a new concept for his art, Elementarism, which was characterized by the diagonal lines and rivaled with Mondrian's Neo-Plasticism.
In 1929 the two men reconciled when they accidentally met in a café in Paris