Theories about contents and purpose

The overall impression given by the surviving leaves of the manuscript suggests that it was meant to serve as a pharmacopoeia or to address topics in medieval or early modern medicine. However, the puzzling details of illustrations have fueled many theories about the book's origins, the contents of its text, and the purpose for which it was intended. Here are only a few of them:

Herbal

The first section of the book is almost certainly an herbal, but attempts to identify the plants, either with actual specimens or with the stylized drawings of contemporary herbals, have largely failed. Only a couple of plants (including a wild pansy and the maidenhair fern) can be identified with some certainty. Those "herbal" pictures that match "pharmacological" sketches appear to be "clean copies" of these, except that missing parts were completed with improbable-looking details. In fact, many of the plants seem to be composite: the roots of one species have been fastened to the leaves of another, with flowers from a third.

Sunflowers

Brumbaugh believed that one illustration depicted a New World sunflower, which would help date the manuscript and open up intriguing possibilities for its origin. However, the resemblance is slight, especially when compared to the original wild species; and, since the scale of the drawing is not known, the plant could be many other members of the same family — which includes the common daisy, chamomile, and many other species from all over the world.

Alchemy

The basins and tubes in the "biological" section may seem to indicate a connection to alchemy, which would also be relevant if the book contained instructions on the preparation of medical compounds. However, alchemical books of the period share a common pictorial language, where processes and materials are represented by specific images (eagle, toad, man in tomb, couple in bed, etc.) or standard textual symbols (circle with cross, etc.); and none of these could be convincingly identified in the Voynich manuscript.

Alchemical herbal

Sergio Toresella, an expert on ancient herbals, pointed out that the Voynich manuscript could be an alchemical herbal—which actually had nothing to do with alchemy, but was a bogus herbal with invented pictures, that a quack doctor would carry around just to impress his clients. Apparently there was a small cottage industry of such books somewhere in northern Italy, just at the right epoch. However, those books are quite different from the Voynich manuscript in style and format; and they were all written in plain language.

Astrological herbal

Astrological considerations frequently played a prominent role in herb gathering, blood-letting and other medical procedures common during the likeliest dates of the manuscript (see, for instance, Nicholas Culpeper's books). However, apart from the obvious Zodiac symbols, and one diagram possibly showing the classical planets, no one has been able to interpret the illustrations within known astrological traditions (European or otherwise).

Microscopes and telescopes

A circular drawing in the "astronomical" section depicts an irregularly shaped object with four curved arms, which some have interpreted as a picture of a galaxy, which could only be obtained with a telescope. Other drawings were interpreted as cells seen through a microscope. This would suggest an early modern, rather than a medieval, date for the manuscript's origin. However, the resemblance is rather questionable: on close inspection, the central part of the "galaxy" looks rather like a pool of water.

Multiple authors

Prescott Currier, a US Navy cryptographer who worked with the manuscript in the 1970s, observed that the pages of the "herbal" section could be separated into two sets, A and B, with distinctive statistical properties and apparently different handwritings. He concluded that the Voynich manuscript was the work of two or more authors who used different dialects or spelling conventions, but who shared the same script. However, recent studies have questioned this conclusion. A handwriting expert who examined the book saw only one hand in the whole manuscript. Also, when all sections are examined, one sees a more gradual transition, with herbal A and herbal B at opposite ends. Thus, Prescott's observations could simply be the result of the herbal sections being written in two widely separated epochs.