Summer Jig is based on the medieval English round ‘Sumer is Icumen in’, which means ‘Summer is arriving’. It is around 900 years old, dating from the mid-thirteenth century. A ‘round’ is a song that can be sung by two or more people, starting at different times. So, in effect, the tune forms its own accompaniment. Some well-known children’s songs are rounds, including Frère Jacques and London’s Burning. Sumer is Icumen in is actually two rounds that happen at the same time – one for higher voices and one for lower voices. The round for lower voices is short, and is repeated several times, while the higher voices overlap with the main tune, which is much longer. The original words, written in ‘Middle English’ have been modernised in Summer Jig, though the metre and rhyming structure are maintained, so the fit with the music is the same.