Choir choral works, though not as numerous as his works for other media, stand out as some of his greatest (such as the "Great" Mass in C minor and Requiem in D minor, the latter of which is often considered the greatest Requiem Mass of all time). Haydn became more interested in choral music near the end of his life following his visits to England in the 1790s, when he heard various Handel oratorios performed by large forces; he wrote a series of masses beginning in 1797 and his two great oratorios "The Creation" and "The Seasons". Beethoven wrote only two
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,