The Modern Forgery Hypothesis

[ReneZ]

As for what I would consider rising to "serious problems", for the 1665/66 Marci letter, I would list that bad Latin;

In 2002, Margaret Garber successfully defended a PhD thesis about Marci's philospohical writings. In the committee was Joseph Smolka, who has studied Marci's life, and published about him continually since the 1960's. The title of the thesis is:

Garber, M.: Optics and alchemy in the philosophical writings of Marcus Marci in post-Rudolphine Prague 1612-1670, dissertation submitted for the degree Doctor of Philosophy, San Diego, 2002.

In this thesis she literally writes that "Marci did not write in the most efficient of manners".
His Latin was cumbersome.

This is a feature of Marci's writing. The opposite of evidence that this letter is not genuine.