Riding his bicycle, smoking a pipe, with his sketchbook on the handlebars, Piet Mondrian (1872-1944) explored the area around the river Gein near Amsterdam. He drew and painted countless series of farms, windmills and groups of trees. In this large drawing of such a row of trees along the Gein, clearly he is searching for a specific balance in the interplay of lines and the contrast between light and dark. The thin, vertical tree trunks are reflected in the horizontal river[PH1] . Not long afterwards, he painted the same trees in extremely bright colors. This drawing heralds a turning point in Mondrian’s painting style: from the dark demure tones of the Hague School to the sparkling modern style of Luminism and, ultimately, total abstraction.