Throughout his career, Khnopff created a series of small 'silent landscapes of heather and woods, stretching on long hills' (letter to Paul Schultze, Naumburg, 1899) at Fosset, a village in the Belgian Ardennes, near Marche, where his family had a summer home.

In these works, Khnopff differentiated himself from the then fashionable taste of human presence in any painted form, with all the formality of light and colour. The one exception he made in this series of 'silent landscapes' is in A Fosset, Un Soir of 1886, where two figures are seen, yet only from behind (see R. L. Delevoy, et alia, op. cit., no. 91).

In the 1904 monograph on Khnopff Louis Dumont-Wilden writes 'De même ces paysages d'Ardennes, ses études faites à Fosset, rien ne ressemble moins aux improvisations lyriques ou aux consciencieuses évocations de nature où se complaisent la plupart des paysagistes belges. Ce que Khnopff a cherché dans le site ardennais, c'est le repos assourdi que représente pour lui la gamme des verts, c'est l'harmonie tendre ou desséchée de ces lignes de coteaux, qui s'étendent jusqu'aux plus lointains horizons la succession de leurs plans bleutés.'

Whereas his countryman and contemporary Felician Rops used the landscape merely as an 'aide memoire', Khnopff felt that nature presents the idea. The basis of all Khnopffian work lies in the belief of superiority of the spiritual over that of the material.