history - Meaning and Usage of "as to be"

The following question is motivated by another question, now removed by the OP, and that I feel it didn't received enough attention.

More than a decade later, about the time that our feudalism was in the last throes of existence, Carl Marx, writing his Capital, called the attention of his readers to the peculiar advantage of studying the social and political institutions of feudalism, as then to be seen in living form only in Japan. Source

In the text above, I found very confusing the use of "to be seen" to refer to a current fact. From the context, I imagine the meaning of this phrase is:

as then seen to be in living form only in Japan

or simply:

as then seen in living form only in Japan

This ngram hints that "as to be" is an expression falling in disuse.

I have tried to locate similar uses, but this has proven to be a "find a needle in a haystack" job because of other more common uses of "as to":

• 
  

  so as to do something "she had put her hair up so as to look older"

  
  


• 
  
  

  so good as to do something "Would you be so kind as to do this for me?

  
  


• 
  

  such a way as to be "Under these conditions, the communications from the more powerful person is structured in such a way as to be totally inconsistent"

  
  

For this question, I'm hoping someone can shed some light on:

• the use of "as to be"


• and perhaps some of the history behind this use.

Answer

This is a confusion of two different expressions:

1. 
   

   as seen, which has a variety of uses:

   
   

   
   

   Chopin, as seen by his pupils ... = how his pupils saw Chopin
   Professor Hunt discusses Keats' relation as a poet to his Elizabethan forerunners, as seen in his love of nature ... = which may be discerned in his love of nature
   As seen on television ... = the same one or of the sort you see on television

   
   
   

   
   


2. 
   

   to be seen, which as used here means approximately which may be seen

   
   

   
   

   Uccello's violent one-point perspective, to be seen in his Battle of Romano series.

   
   

   
   

The author of this passage was not a native speaker; but he was highly educated and a very literate writer. I think his mistake arose because he was trying to say two things at once: that in Marx' day feudalism as a living form was to be seen only in Japan, and that Marx was inviting his readers to examine feudalism of the sort you see in Japan.

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By the way: I think you can ignore that Ngram. I glanced at fifty or so the hits and they were all components of different constructions, mostly so as to be = in order to be or so ADJ as to be = so ADJ that it was.