This book is about the power of variety – a power with which we moderns are well-acquainted. Our appreciation for variety has deep roots. As far back as the eighteenth century, the poet William Cowper wrote, ‘Variety's the very spice of life / That gives it all its flavor.’ Cowper's words have since become an oft-repeated proverb, because they capture the common view of variety as a valuable if ancillary player in the drama of life. After all, variety is seasoning, not sustenance; we can live without it, just as we can easily gain nourishment from a flavorless meal. But our enjoyment of both food and life is diminished without the ‘spice’ of variety.

This association of variety with pleasure quickly lends itself to moral judgment. Social commentators of all ideological bents frequently bemoan the culture of distraction that has gripped contemporary minds, thanks to the infinite variety of pleasures supplied by the internet, and the ease with which those pleasures can now be accessed anywhere, at any time (even during the spiciest of meals!). Yet this is not a purely modern concern. Critics have long recognized that our natural inclination to delight in variety says something rather disturbing about the human psyche. Cowper himself expressed similar sentiments. In the lines following his now-famous maxim, he suggests that variety is valued only because it offers a never-ending supply of amusements, whose sole purpose is to cater to humans’ regrettably short attention spans. (One can only imagine what Cowper would say about social media.) We moderns thus think of variety as a double-edged sword: on the one hand, variety embraces the rich diversity of human experience, but on the other, it encourages only a superficial engagement with that diversity. This is true of literary variety as well: we value exposure to a wide range of voices and modes of expression, but we shun tokenism.

The Middle Ages had its own understanding of literary variety, which sought common ground between these two extremes. Medieval writers defined variety (Latin varietas) as the mixing of different styles or structures in the same work, for the purpose of creating aesthetic and conceptual harmony. Importantly, writers could not simply vary the style or structure of their works at random and expect to create this kind of harmonious varietas.