For several centuries, people have looked at the Voynich Manuscript’s mysterious pictures of plants and wondered how on earth they fit into any of the traditions of medieval herbal manuscripts.
Certainly, there are a handful of places where you can just about see similarities: but though (for example) the heads in the roots of the plant on f33r do vaguely resemble stylised illustrations of mandragora, the plant depicted there is nothing at all like mandrake. And so the widspread presumption that it is some kind of enciphered herbal has little to commend it.
But recently, Glen Claston has put forward a radical new suggestion: that the Voynich’s plant drawings might actually be encoding secrets of herbal gardening, such as how best to prune individual plants. If this surprising idea is true, it would place the herbal part of the Voynich Manuscript within a completely different written tradition – books of agriculture.
One book on agriculture dominates the medieval era: the Ruralia Commoda (~1305) of Pietro Crescenzi. Its twelve chapters covered (1) where to place buildings, (2) where to plant crops, (3) cereals and granaries, (4) viticulture and vinification, (5) & (6) arboriculture and horticulture both for medicine and food, (7) meadows and woods, (8) gardens, (9) animal husbandry and apiary, (10) hawking / hunting, (11) a summary of (1)-(10), and (12) an agricultural calendar, arranged by month. It was widely copied in manuscript, and in 1471 became an early print best-seller.
Unfortunately, because its well-known contents are fairly prosaic, they would seem to be an unlikely source for anything to be found in a heavily-enciphered book of secrets. Yet because agriculture was essentially a kind of natural magic, there is a (fairly marginal) literature on books on agriculture to be found, initially by consulting Lynn Thorndike’s various works.
In “Science & Thought in the 15th Century”, Thorndike briefly mentions Pietro Crescenzi (p.219), and points to a 1922 paper by Luigi Savastano: but Crescenzi’s general level-headedness (he thought wine should be left to sit for a year before drinking it, for example) sits is in sharp contrast with contemporary superstitious / magical agricultural beliefs, such as the peasant ritual for producing large carrots (“Long as my thigh, big as my head” – History of Magic & Experimental Science IV, p.276) or the notion that a full-size cucumber could be grown from a specially-prepared seed in an hour (HoM&ES III, p.139).
For the fifteenth century, Thorndike mentions BN 7483 (HoM&ES IV p.435), a small work on agriculture that an apostolic abbreviator called Benedetto Maffei (d.1494) dedicated to Lorenzo de’ Medici, and which discusses the influences of stars on agriculture. Incipit: “scripturus ad te vir maxime atque doctissime exiguusque stuiorum moerum munus exhibiturus“. (Iter Italicum p.58).
Thorndike also notes (HoM&ES IV p.442) that the printed editions of Regiomontanus’ Ephemerides (such as Hain * 1303 and Hain * 13794) had discussions on stars and agriculture: this also appeared in MS Prag 742 (15th century, 31 folios). There is also some discussion of agriculture in the pre-1396 medieval encyclopaedia “Fons memorabilium” (HoM&ES IV p.565).
However, Thorndike’s most suggestive mention of a possibly-secret book of agriculture has been extensively mentioned here before: in “Science & Thought in the 15th Century” p.219, he discusses how Giovanni Michele Alberto described a (now-lost) herbal by Antonio Averlino (Filarete) as having been written “elegantly in the vernacular tongue“, and wonders whether this might be the (also lost) “books of agriculture” described somewhat coyly by Filarete in his libro architettonico. Admittedly, this is a somewhat thin reed to cling to – but one which is discussed in more detail in “The Curse of the Voynich” (2006).