For Giersing, landscapes and woodland pictures were, like still lifes and portraits, genres not demanding closer explanation when he occupied himself with them. According to tradition they were simply per se artistic picture types. But perhaps there was a more cynical reason for engaging on with nature motifs, a reason which it is impossible entirely to ignore, that is to say the financial incentive that landscapes and woodland scenes were easier to sell than portraits.
When he again started painting landscapes he had serious problems. In spring 1911 he had seen Cézanne's Avenue at an exhibition and been wildly enthusiastic. In August 1911, for the first and only time, he visited Christiansø, and it might well have been expected that its natural scenery, which is probably the closest you can find in Denmark to Cézanne's native region, would be an ideal source of inspiration to Giersing, as it was for Karl Isakson and Edvard Weie. But that was not the case.
In 1912 he painted in Grib Forest in northern Zealand. The forest was "absolutely wonderful", but it was also "difficult to paint". He managed to paint 14 pictures, but was only satisfied with two. As before, he was inclined to let a path or track structure his forest motif, which was walled up green in green with a host of intermediate shades which blend to fon1l a delicate, silky harmony, using a mixture of parallel and loosely characterising lines. The results were however often strangely ineffectual in structure. Mastering the values was not enough; they also needed to be concentrated, as he wrote in a review in 1910. In summer 1914 at Mogenstrup near Næstved in Zealand he found a solution to the problem of getting to painterly grips with the Danish natural scenery by means of a manner of painting that was both rougher and more disciplined. Through stronger contrasts and by choosing the palette knife rather than the brush he was able to produce the form and character he sought. The motif elements are those of the Danish landscape tradition stretching back to the so-called Golden Age in Danish painting from the first half of the 19th century. In Road near Mogenstrup the road opens from the bottom edge and as it were draws the viewer in, the trees flank it and arch above it, and then in the background there is the radiant opening. But this and others also touch on something in which the painters of the Golden Age were not normally interested, that is to say the double moven1ent of the viewer's gaze being met by the picture's gaze. The classic modernist work, whether it be expressionist or cubist tends towards the dissolution of the viewer's perspective to the advantage of that of the picture.
Giersing spent the summers of 1915 and 1916 in Sorø, where he was very productive indeed, although the weather was bad. He always needed to stand directly facing the natural scenery when he painted it. The method of painting became wilder, more spontaneous, and the treatment of the motif and the artistic expression consequently more open.
The double moven1ent towards the intimate and the closed and the more monumental shifted from 1915 to 1916 towards a more unambiguously dramatic intensity. The palette knife's green, greasy strokes, gathered together in chaotic surfaces, is replaced by resolute brush strokes forming surfaces by means of visible parallel strokes or thinner, emphatic surfaces like surface eruptions contrasting sharply with each other. The ornamental, organic arabesque is replaced more and more by the crystalline. In brief, the form becomes more aggressive and determined.
From the point of view of sales, Giersing had success with his forest pictures, probably because, despite all the intensity, his interpretation of nature was "related to older Danish landscape painting", as one reviewer put it.
In 1917 Giersing moved from the forest out into the open landscape, from the enclosed space to the open, from the potentially chaotic to the well organised architectural, and from the vertical to the horizontal, when he painted broad spreading landscapes around the Furesø lake north of Copenhagen. In composition most of the landscapes from that year are fashioned in the same way: a broad foreground, where a road-like wedge or a row of bushes or trees draws the eye in towards the background, usually the edge of a forest, with the sky arching above. The compositions are rigorous, the movement and the colour combinations simple, often light green in the illuminated surfaces and blue in the shade, the whole held together by simple forms and surfaces, but not so simplified that the pictures cannot be seen as landscapes in a quite conventional sense. In the Furesø pictures from 1918 Giersing intensified the geometrical stylisation so that the arrangemel1t seemed more calculated and the effects some-times more vehement, less charming than before. So they did not seem natural to the arbiters of taste of the time, who backed off.
Giersing's artistic relationship to nature is expressed in the aphorism "Nature is nothing, the picture of it everything" (1917). By this he did not mean that naturalistic art is of no value. The meaning was rather exactly what the words say, that is to say that nature is nothing but the picture we ourselves make of it. The conclusion must be that what Giersing believed the use to which painting could be put was to mediate between on the one hand reality, which was impossible, intangible and far too ugly and chaotic, and on the other what was far too possible, too confidently seized on and too conventional. And he did so in a way in which this mediation was both form and content. It so to speak created what it was - for instance a woodland scene or a landscape.