Whereas in "The Creation" Swieten was able to limit himself to rendering an existing (anonymous) libretto into German, for "The Seasons" he had a much more demanding task. Olleson writes, "Even when Thomson's images were retained, they required abbreviation and adaptation to such an extent that usually no more than faint echoes of them can be discerned, and the libretto often loses all touch with the poem which was its starting point. Increasingly during the course of the oratorio, the words are essentially van Swieten's own or even imported from foreign sources."