Early musical traditions during the 17th and 18th century saw the emergence of more complex carols, away from the repetitive ceremonial songs. These carols featured complex poetry based on cynghanedd, some were sung to English tunes, but many used Welsh melodies such as 'Ffarwel Ned Puw'. The most common Welsh folk song is the love song, with lyrics pertaining to the sorrow of parting or in praise of the girl. A few employ sexual metaphor and mention the act of bundling. After love songs, the ballad was a very popular form of song, with its tales of manual labour, agriculture and the every day life. Popular themes in the 19th century included murder, emigration and colliery disasters; sung to popular melodies from Ireland or North America.