An alchemical mass seems like a curious piece of writing, and indeed the text edited and investigated in this book is the only known example of its kind. Nevertheless, Didier Kahn's attention to philological and historical detail turns it into a lucid case study which throws into relief the relationships between alchemy, religion and their literary forms across the late medieval and early modern period. The critical edition of the short text of the mass usefully places its known Latin versions (all after 1580) alongside one another where they differ, and even adduces a Czech version, given in transcription, transliteration and a re-translation into Latin for comparative purposes. Careful examination of the sources dates the origin of the text not to Melchior de Sibiu, a Transylvanian priest decapitated in 1531 for counterfeiting gold coins, but to the mid-fifteenth century. In this late medieval context, which saw a whole range of different genres of masses, including parodic ones, an alchemical mass would not have seemed out of place, and certainly not shockingly outlandish: a playful pastiche drawing allegorical parallels between the life, death and resurrection of Christ, and the ‘great work’ of making the philosophers’ stone. The late sixteenth-century copyists and publishers of surviving versions of the mass, Kahn argues, show a similarly carefree attitude towards this literary game. Despite their well-defined confessional leanings (Calvinist, Schwenckfeldian, and Paracelsian theosophy), they refrain from any theological commentary on its liturgical form, focusing instead on the alchemical process. Although this is in itself likely to be a reflection of the Protestant relegation of the mass to a mere commemorative rite, Kahn points out that the text does not serve as a vessel for religious polemic, but rather as a playful and evocative way of packaging practical alchemical content. This is a welcome corrective to previous studies of this mass which, following C. G. Jung, have over-emphasised the religious symbolism of its liturgical elements by reading it as an expression of psychological processes, thus obscuring the alchemical practica at its core. During the first half of the sixteenth century, the reception of the alchemical mass changed. Such spiritually diverse commentators as Michael Maier (a Rosicrucian), Andreas Libavius (a Lutheran) and Athanasius Kircher (a Jesuit) increasingly expressed discomfort or even disdain at the text's amalgamation of the sacred and the profane. What had been seen as a playful pastiche now had to be disentangled – in Libavius’ case by toning down the liturgical and extracting the purely alchemical; for the Jesuits, by a wholesale rejection of Rosicrucianism and indeed any alchemical interpretation of Scripture. Overall, Kahn's edition and analysis of this puzzling text not only succeeds in dating its origin to a literary and religious context which makes sense of its apparent oddity, but also traces its reception across time and confessional boundaries, highlighting the fluctuating connections between alchemy and religion, as well as changing attitudes towards their written forms.