Epode is a poetic form made up of two lines that differ in structure and frequently in metre, with the second being shorter than the first. An epode is the third section of the three-part structure of Greek lyric odes, following the strophe and the antistrophe. The epode usually concludes with a tercet, which in turn gives rise to the French term "tercet". Literary theorists have discussed at length the origin and development of the epode. Some believe it to be ancient, while others argue for its modern nature. What can be said with some certainty is that it was widely used by both Old and New Testaments poets. In classical literature, the epode is found mainly in poems written in iambic meter, but it also appears in lyrics written in dactylic (10-syllable) meter and in hymns written in dactylic (12-syllable) meter. The epode is generally considered to be one of the most difficult genres of Classical Greek poetry to write well because it requires a great deal of skill in balancing repetition with variation. This difficulty may explain why it has rarely been achieved successfully after its inception. In English literature, the epode first appeared around 1450 and was popular among all kinds of poets, from John Lydgate to William Wordsworth.