Matthew Locke’s provocative decision to entitle his 1675 published score of Psyche ‘The English Opera’ has been seen as a direct response to the apparent threat posed by the 1674 production of Ariane in London, and the public appeal the French musicians involved had made to Charles II to sponsor their proposed new ‘Academy of Opera’s’. Locke had been key to developing Restoration music-drama and was the senior London theatre composer of the 1670s; it is therefore easy to see his self-published score of Psyche as a manifesto for English opera. Scholars have largely interpreted this manifesto as “a vigorous defence of the practice of mixing music and spoken dialogue on the stage” (Price). Yet in the preface to ‘The English Opera’ Locke stated clearly that it was Shadwell who determined the part-sung, part-spoken form of Psyche; indeed, Shadwell himself claimed that he had controlled the distribution of the music and “what manner of Humour I would have in all the Vocal Musick”. Locke’s preface placed the musical emphasis elsewhere: while explaining that he took pains to fit the musical ‘humour’ to the text, he focused primarily on its variety, such as “was never in Court or Theatre till now presented in this Nation”. The concept of variety – which contrasts with modern notions of structural unity – was central to creativity in all fields in this period, and it was discussed extensively by contemporary writers on music, most notably Thomas Mace and Roger North. In this paper I use surviving accounts of variety and ‘humouring’ the text as a starting point for analysing Locke’s musical vision for English opera, and as a preliminary means of assessing how we can develop a more historically contextualized understanding of the structural principles used by Restoration composers for their large-scale works.