“Mirie it is while sumer ilast” (“Merry it is while summer ylast”) is a Middle English song of the first half of the 13th century. It is about the longing for summer in the face of the approaching cold weather. It is one of the oldest songs in the English language, and one of the few examples of non-liturgical music from medieval England. The manuscript was found together with two old French songs in a book of Psalms in the Bodleian Library. It was rediscovered at the end of the 19th century and made accessible to experts in 1901. It was arranged and published in a modern form for the first time by Frank Llewellyn Harrison.