Brief overall guide. I’ve grouped by style as well as evident content. I hope this will allow the individual posts to be set in context.
1. Botanical folios. (Hellenistic with evidence of eastern retention)
Each image represents a group of plants, classified in a way that is explicable in terms of works written by Theophrastus of Eresus, though quite unlike the Dioscoridan system, or our modern taxonomic classes. While some later works made in Europe have echoes of similar style in their imagery, none are closely akin to the informing system, or to the attitude which is reflected in these folios – with one or two exceptions. Folio 9v appears to me to be constructed by someone accustomed to the Dioscoridan style, but who has evidently been instructed in this other. Folio 9v is also the folio which has a line of extremely fine script written on one of the flower petals, a script which appears to resemble Hebrew but which an expert informs me was not been written by anyone trained to write that script. It is often forgotten that a scribe’s hand has to be trained to write any script fluently and evenly, and the efforts of a non-native – even one trained in a different language and script – are usually manifest to anyone with formal training in the one concerned.
Overlaid on that basic stratum which, in my opinion, is Hellenistic, is evidence of affect from local customs in art, and these are evidently those found east of the Indus.
There are, in addition, mnemonic elements and other cues that have been added at some later stage, and which serve to explain the plants’ relationship to each other and their shared or inter-dependent uses.
Between some of these cues and their style of drawing, we find close similarity of form, though not evidently of meaningful intent, in a famous copy of Dioscorides, that known as the ‘Mashad Diosorides’, which was made in the twelfth century AD – when:
several princes of the Turkoman Urtuqids revived the Greek, Syriac, and Arabic tradition in its original home, in various cities between the upper Tigris and Euphrates Rivers in the Diyar Bakr district. 
 Florence E. Day, Mesopotamian Manuscripts of Dioscorides’, The Metropolitan Museum of Art Bulletin, New Series, Vol. 8, No. 9 (May, 1950), pp.274-280. (p.275).
This aspect of the botanical images will become important when I return to discussion of the separate chronological strata, and consider this same region around Diyabakir. There, by the twelfth century if not earlier, we find an absorption of east Asian custom, joined with habits very similar indeed to those informing the Voynich ‘root mnemonics’. It is apparently this region which provides us with a point of intersection between the stream which brought the Voynich botanical folios on the one hand, and on the other the type of imagery which informs some Latin herbals, into the west.
The difference is that the copies made in Arabic for Arab or Turkish rulers use the conventions in a purely formal way, whereas in the Voynich manuscript we see them employed as a systematic, well-informed, and elegant ‘code’.
The key to a folio’s selected plants, as a ‘group’ has partly to do with similar appearance, but (as it seems to me) much more to do with the users’ knowledge that these are of similar or complementary use and of commercial value. Little interest is shown in any flower, except as it has independent commercial value or is the only way to determine one variety over another. The last criterion is standard in western taxonomy, but rare in the Voynich manuscript, just as it is in Theophrastus’ works.
Overall, the dominant influence here, overlying the Hellenistic basis, does not come from upper Mesopotamia but from regions adjacent to the eastern sea. It is there that, for example, water plants are habitually shown with their roots hair-like and floating.
I cannot stress sufficiently that the botanical drawings are not poorly drawn, but very clear and immensely practical; their interpretation requires explanation of every part of the drawing, because every element in the picture is germane. Too often, in the effort to force a parallel to the western herbal tradition, commentators have exaggerated some part of the drawing which agrees with their theory, while dismissing those elements which plainly contradict it. By ‘elements’ I mean not only the system informing the folios, but such things as relative proportion.
When addressed by conventions proper to their own visual language, these deserve to be described as ‘realistic’ figures for their consistency, accuracy in representing leaf, petiole and habit, and for their being plainly informed by first-hand knowledge of the plants themselves.
While the Voynich may, one day, prove to be written in Arabic, or Latin, or Greek, I do not see any evidence of the Christian or Muslim habit of condemning the ways of other religions. Among the botanical folios are some which seem to allude to religious festivals, and (unlike some diagrams in the astro-meteorological section), they have an entirely neutral tone. Muslim and Christian works, even herbals, cannot forbear from discriminating in favour of their own religion and its members.
2. The ‘pharma’ section, so called. (Far eastern)
Closely linked to the botanical folios, this section carries some hint of an earlier classical stratum, but overall evokes chiefly the style of Siddha, Ayurvedic and most obviously the type of the ‘Bencao’ handbooks. It was long believed that the older work known as the Shennong bencao jing was no longer extant, with the later work by Li Shijen  produced only in the sixteenth century, but even though the former has apparently been recovered * there is no doubt that the habit of depicting plants by ‘root and leaf’ is characteristically far-eastern. That printed herbals were earlier available is known, as is their being employed to inform merchants’ inventories and to assist lading and taxation. In centres such as Guangzhou, Cairo, Alexandria and Tunis, tax of 20% on goods was not unknown.
 Bencao gangmu (the “Great Pharmacopoeia”). Illustrations can be seen online.
There does not appear to me any particular emphasis on medicine in the Voynich botanical and ‘pharma’ folios, though one expects to find some.
Plants were valued for many other reasons in the eastern trade: as dyes, aromatics, food, timber, and materials for ceramic glazes among them. Overall, the greatest part of the eastern trade consisted of fabrics, aromatics and Chinese ceramics. We are told that late in the thirteenth and early fourteenth centuries, when Genoese were building their own ships in eastern sea, Chinese ships carried eastwards ten times as much as was traded towards the west.
2. The astro-meteological section (Pt 1) (fols 67r -69v, excluding folio 68r i-iii).
Motifs which may fairly be described as ancient are present in this section, and unlike the botanical and ‘pharma’ sections, they show remarkably little evidence of evolution or alteration. Indian and Asian stylistic influence is absent. In my opinion this section originated in the late Achaemenid-Egyptian and early Hellenistic era. The calendar section reflects origins in the same or a closely similar western environment.
Folio 67r-1 is especially interesting, because together with fol.68v-3 it presents as a circular folding book or fan, shown torn on a couple of the inner fold lines, which suggests an exemplar made from palm-leaves, papyrus or – possibly – paper.
The nearest extant parallel is shown below, a religious calendar fan from Christian Ethiopia. The illustration, and the next, were first published on ‘Findings’ (27/04/2010) and I regret that I must reproduce them here from those files, without proper attribution, having recently lost my collection of images and much of my earlier research. Readers’ advice on sources would be most welcome.
Folio 68r-1 to 68r-2 are inconsistent with the rest of this section. Poorly drawn, and lacking certain characteristic indicators typical of the rest in this section, they even betray an uncertainty over conventional motifs for representing sun versus moon. I consider them relatively late, possibly copied from mosaic or wall-painting, but the copyist I should think had no training as a draughtsman or scribe and may have been European.
folio 67r-1 shows a similar effect, though it is more competently done. This diagram includes four superfluous emblems which I think were probably added in Asia minor around the twelfth century or so. Folio 67r-2, on the other hand, appears to me a very true copy, made without alteration, of an original from the early Hellenistic era.
3. The Calendar. ff.70r – 72r; 73r-75r
I believe that it is an error to suppose that the manuscript’s eleven images ever formed a zodiac in the usual sense. Many have argued for a loss of another two images but by factoring those in we are presented with a thirteenfold series – which is still not a classic (Roman) zodiac. Among its thirteen figures, one would have to account for the presence of two goats and two ‘bulls’ – not characteristic of the 12-figure Roman zodiac.
One might, of course, argue that a thirteen-fold series refers to the months of a lunar year, and that the doubled goats and bulls represent intercalary months in keeping with the usual form of lunar calendars. That would be a reasonable theory, but more precise explanation would still be necessary. The fact is simply unavoidable that the manuscript as we have it, and even as it is theoretically reconstructed, apparently contained no zodiac in the strict sense.
I describe it as a ‘calendar’ on the general assumption that the inclusion of stars will refer to the passage of time, but there are certainly other possibilities. Each might, for example, represent the stars visible which are visible at a given latitude, marked perhaps by eleven (or thirteen) cities. It might not represent a calendar at all. As example, the illustration below comes from the Duomo (cathedral) of Siena. This marble inlay represents the ‘constellation’ of towns around Siena. The city itself is represented by Romulus, Remus and the wolf, and those around it are similarly represented by an animal and the city’s name in Latin. Rome is represented by the elephant, and Lucca by a rather lovely leopard. In the same cathedral, between 1265 and 1268, Pisano carved a marvellous pulpit, where animals beautifully rendered crowd the relief. These include two finely rendered camels.
4. ‘Naked souls’ folios (72v; 75v; 76v-84v).
Grouped purely by their distorted ‘human’ figures which I take to be personifications, defined principally as stars.
* the ‘calendar’. Basis in the Achaemenid – early Hellenistic period. Linked especially to the eastern Mediterranean and northern Syria. Many of the centre-motifs would appear to have reached, or survived in, the south parts of the Carolingian empire, where they appear as non-standard figures in copies of the Arataea during the ninth and tenth centuries. The standing archer is of particular interest to us, of course. It apparently derives from Palestine and (as a figure for Saggitarius), from Jewish precedents.
The Voynich image seems to me to be connecting the classical description of Saggitarius as incomparable hunter, and accounts of the Parthians, whose ‘Margian steel’ had struck terror as well as steel into the heart of the Roman army near Harran. Whether the later European copyists understood rightly the distinction between ‘Persian’ and ‘Parthian’; between ‘Magian’ and ‘Margian’  is uncertain. But in the east, the standing archer is a figure seen in zodiac roundels by the sixth century AD.
 Plutarch, “Crassus,” 23-24.
 a reference to Margiana, or Merv. Archaeology has shown a flourishing metallurgy in Marv. It was formerly the Achaemenid Satrapy of Margiana, later called Alexandria, and ‘Antiochia in Margiana’. A major oasis-city of central Asia on the east-west ‘silk road’ routes.
Those various emissaries and missionaries who went east from the thirteenth century onwards passed through the same region, and that marked on the map as Media is where advanced astronomical studies, and correction of the old Ptolemaic data, was accomplished before the time of Gregory Chionides. (As a point of interest, Richard Burton records that playing cards were known to the Arabs and Egyptians as ‘tars daylani’ – Median shields.)
‘Naked souls’ are seen in two other sections:
The last appear to me to treat the interaction of stars, land and elements (including winds and water). They follow the style of the ‘bathy’ folios.
I see no reason to connect any more directly the post-Hellenistic history of the bathy- sections with that of the ‘calendar’ roundels. The ‘ladies’ who provide their common element may not have always had so much in common – except that at some stage religious, social or professional convention decided that no human form should be represented as it appears in life.
I ascribe the custom of marring and distorting human(-like) forms to eastern Jewish custom in deference to Panofsky’s opinion, though this doesn’t preclude a direct input from community or practical profession. Mariners, in particular, are notoriously rule-bound.
5. The world-map. folio 86v. Probably originating in the Hellenistic era though with very strong evidence of Asian affect, overlaid with additions and adjustments which I would date to not later than the early fourteenth century.
6. The “items” section. ff.103r – 116r.
Order and disorder.
There are signs of haste evident in the order and finish of our manuscript. Nick Pelling has studied this question in depth, and while I do not entirely agree with his conclusions, he is (I think?) the only researcher to have initiated and carried out the necessary research. I understand that some of his results may appear elsewhere, but as always I recommend consulting the original source. I will discuss my own views on the matter, time permitting, later this year.