Rosettes and Revelations Pt.1: The Holy City - Koen Gheuens and Cary Rapaport

[Koen G]

Thus the TAU becomes for us a symbol of permanent conversion, the seal of the Kingdom of God, a call to the service of others. 

Yes! I did not know about the meaning of this symbol, but apparently it was quite popular. There was also one of the popes who was obsessed with it.

Cary and I debated for a bit whether or not we should include the tau reference. This is what we learned from the literature:

* What we Voynich reseachers are used to calling "T-O maps" are nowadays called "T-O diagrams" by specialists. This is to distinguish them from actual maps with a T-O structure, like the You are not allowed to view links. Register or Login to view..
* T-O diagrams are an indicator of Christian culture and a Christian worldview, especially by the 15th century.
* While the origin of the diagram itself is debated, there appears to be some consensus that the T would have been seen as a form of the cross.
* We know of no medieval sources explicitly linking the TAU cross in T-O diagrams to the TAU used to mark the elect, converts and so on.

This is why we chose to present the information about the meaning of TAU, but as an advanced possibility. The T-O diagram as a representation of the Christian world is the basic, uncontroversial assumption.

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Michelle kindly alerted me of a duplicate image, which has been fixed now. This is the castle-with-stars in the Dominican's fresco: