Why is the MS not a copy of older, non European sources?

[ReneZ]

Most people seem to think that the content of MS Beinecke 408 was created at the time of its writing in 15th century Europe. The images are peculiar, but this is seen as the result of an individual's quirks, rather than unexpected cultural influences.

You can't assume what other people assume.

This single line from JKP more or less summarises my thoughts as well.

What makes you think peoeple don't consider this possible?
As said many times, both herbal and astronomical/astrological illustrations trace back all the way to the beginning of the 'common era' and before.

This page on my web site here:
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is entirely dedicated to the creation of the MS and does not enter into the question what it contains, what it was based on, or what may have been its sources.

While decades ago, the illustrations were called 'unique', unparalleled and similar other terms, by now it has become very clear that there are plenty of inspirations from other MSs that would have been available at the start of the 15th Century.
Some of these trace back further in time, others don't.

Finally, the meaning of non-European probably isn't the same for everyone.
The original composer of the Latin 'pseudo-Apuleius' herbal is believed to be native from North Africa, but copies of this herbal were circulating all through Europe by the 12th and 13th Century.
There have been plenty of suggestions that the MS was made in (or contains information from) meso-America or the far East, but such suggestions require strong evidence, much stronger than what has been presented so far.