Evidence that Chaucer's language was perceived as difficult appears quite early. Thomas Speght's 1598 edition of Chaucer, for instance, contains a glossary entitled “the old and obscure words of Chaucer explained.” Most famously, the poet John Dryden undertook to translate three of Chaucer's tales in his Fables, Ancient and Modern. Dryden acknowledges that some readers prefer to read Chaucer in the original and that to translate the poet is to sully his poetry. There are certainly some learnable and teachable skills that can make the experience of reading Chaucer easier and more enjoyable for students familiar with the conventions of English poetry. Nearly every critical or teaching edition of Chaucer's works features a phonetic chart or list that indicates the etymological history and pronunciation of his vowel sounds.