Often regarded as a private activity, Cézanne's work in watercolour increased towards the end of his life and from the 1890s onwards shows a free and confident style. Cézanne's landscape sketches are testimony to this, and the work Paysage boisé shows Cézanne loosening his square, diagonal brushwork of the 1870s and adopting a softer, yet still lucidly structured style. One can see how Cézanne's eye was instinctively attracted to the rhythmic arrangement of the verticals of the tree trunks, their outlines drawn swiftly in pencil. Pencil lines do not imprison the forms, but merely suggest them, and elsewhere indicate shaded areas to guide the brush. Cézanne has begun to use softer, more opaque colours to create a wonderfully, decorative impression. Transparent washes of blue, violet and green create the effect of light and foliage, with untouched areas of white paper also playing a descriptive role. Rewald writes of a similar work from this period, "It is one of the unceasing mysteries of Cézanne's watercolours that delicate washes of blue, pink, yellow and green - lightly scattered across a white sheet - can conjure up an image provided with all the essentials and devoid of anything superfluous. In front of such a superb achievement, the question of "finish" or "unfinish" becomes academic." (John Rewald, loc. cit., p. 199)