This year I have worked hard, and done much searching. A great deal of the old [way of painting] was due for a change. I was searching for a purer representation, which is why I wasn't satisfied with anything... The large black and white one ['Composition in line', 1917] has also been totally reworked, which I now regret; it would have been better to leave it as it was, and make a new one. But when one is searching, one does not now in advance just how to go about it.

Letter to H. P. Bremmer, 7 March 1917