The Creation structure but may be written by an unknown author. Back in Vienna, Haydn passed it to his friend and sponsor Baron Gottfried van Swieten, who translated and organized it. The sources for the libretto are the two Creation narratives from the Book of Genesis, some Psalms, and John Milton's "Paradise Lost", an epic poem in ten volumes, first published in 1667. The libretto is structured in three parts, the first dealing with the Creation of the universe and the plants, the second with the Creation of the animals, and of man and woman, and the third with Adam and Eve in
The Seasons (Haydn) was based on extracts from the long English poem "The Seasons" by James Thomson (1700–1748), which had been published in 1730. 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,