Thomas Morley (1557/8-1602) has long been regarded as the most important English music theorist of the early modern period. His treatise, A Plaine and Easie Introduction to Practicall Musicke was published in a luxurious folio format in 1597 and a second edition appeared in 1608. The three parts of the treatise set forth elementary music ('teaching to sing') and beginning and advanced counterpoint ('treating of descant' and 'treating of composing or setting of songs'). The text, written in dialogue format, is enlivened by remarkable descriptions of music, musicians, musical performance and compositional practice. Jessie Ann Owens introduces the facsimile, explaining why the 1608 version has been chosen.