Mirror-images often occurred when woodcuts and engravings in general where copied from drawings. So a possible explanation would be that the Voynich illustration was copied from the print of an engraving (that was mirror imaged). Given that the Voynich zodiac illustrations are so original, I think it is not very likely that they were directly copied from anything, still this would explain the mirror-image / reversing.
I attach examples by Albrecht Durer.
![[Image: attachment.php?aid=550]](http://www.voynich.ninja/attachment.php?aid=550)
I attach examples by Albrecht Durer.
![[+]](https://www.voynich.ninja/images/collapse_collapsed.png)