Currier A and B

[Emma May Smith]

Now, what's the reason?

The writing system is the same. That's important. What might differ might be the underlay plain text language (e.g. Dialect 1 vs Dialect 2) - in the case we have an unknown natural language here, or the encryption procedure - in the case we have a cipher here.

Let's consider the natural language case first. In that case we have two persons writing different languages or dialects in the same writing system. (Or one person writing those in different periods of his life). Now, even one rare language with an unknown writing system is something extraordinary, but two persons writing a single volume using different languages or dialects and using the same writing system for that is something that I would call not very probable. Likewise he would be a strange single author who started in one dialect and ended with another - both in the same writing system. The problem is not with a single writing system for two different languages - e.g. English and Latin both use the same alphabet - but with the single writing system unknown to us for two different (rare or extinct) languages.

Both the script and the language could be the same, but the orthography may be different, which is indeed very likely if the script or the language were not commonly written. Here are lines from a Middle English poem, in two different manuscripts:

Þeos vle abod for hit wes eve, // Heo ne myhte no leng bileue,
Þos hule abod fort hit was eve, // ho ne miȝte no leng bileue,

You can tell they're the same text and basically the same language. But 6 of the 13 words have different spellings.

Backing up this idea is that the orthography of the Voynich text clearly shows evolution throughout the manuscript. I believe that this may be the underlying cause of A and B: the writer made changes to their orthography throughout the writing process, and the changes built up significantly so that the text looks quite different between beginning and end.