This recording is the first of a collaboration between René Jacobs, the Kammerorchester Basel, the Zürcher Sing-Akademie and Alpha Classics and will involve the release of four albums between 2025 and 2028; the first of these is the Missa Cellensis, then three albums devoted to Haydn’s last six masses. Haydn was commissioned in 1766 to write a Missa solemnis, the Latin term for a fully scored mass with trumpets and timpani; it is the third and largest of Haydn's fourteen masses. It was under this erroneous name that the 1766 Missa Cellensis remained known until 1975, when a fragment of the autograph score containing the title page, Kyrie I and Christe was found in Bucharest and revealed that Haydn had in fact composed two Missæ Cellenses. It is the first of these (1766) that is recorded here. René Jacobs puts all his expertise and enthusiasm at the service of this music that he loves so much, in collaboration with soloists with whom he works regularly, an orchestra that is also a longstanding partner, and the remarkable choir of the Sing-Akademie of Zürich.