Has <PERSON> almost-identical plagiarism from an 1850 book by <PERSON> already been described in the literature?
Background. I have made an observation, documented in detail in https://twitter.com/LGcommaI/status/1116010801784152064. [ I am the person who is writing the content of the twitter-channel @LGcommaI; this is not plagiarism of the observation. ]
Preliminary epistemological remark. Obviously, strictly speaking, such an almost-identical agreement in conjunction with <PERSON>'s book being two decades younger than <PERSON> merely strongly suggests that <PERSON> plagiarized from <PERSON>, but does not prove it. 321
(For vavious reasons; e.g., there remains the remote theoretical possibility that there existed a third (unnamed) source which both <PERSON> and <PERSON> plagiarized from.
Description of the observation. For your convenience, I will repeat my observation here: in <PERSON> 1871 book Morals and Dogma there is a passage of about twenty lines which occurs almost-identically on page 6 <PERSON> 1850 book Progress Of The Intellect. (Documented at https://www.docdroid.net/4kKUlnt/did-albert-pike-plagiarize-from-robert-william-mackay.pdf). No mention of <PERSON> is made by <PERSON> anywhere.
<PERSON> made exactly three changes to <PERSON>'s paragraph:
(1) <PERSON> replaced "under different" by "with only a change of"
(2) <PERSON> freshly inserted the subclause
"when his ancestors communed face to face with the Gods;"
into <PERSON>'s paragraph (which does not contain any such statement), after the main clause "man still looked back with longing to the lost golden age" (which is identical in both sources).
(3) <PERSON> chaged the somewhat nonstandard spelling "<PERSON>" into "<PERSON>"
I think that these minor differences are all.
I would be surprised if this hasn't been published before in one-and-a-half centuries already, but (so far) I haven't found it in the secondary literature, whence my:
Question. Has this particular case of almost-identical plagiarism been described in the published literature? (I.e., not only the generality that <PERSON> may have plagiarized occasionally here and there, but this particular instance.)
Appendix. For the sake of self-containedness, I add my side-by-side comparison of the two passages as image-files.
All in one picture:
Part of the same image split into several images:
(Adding more images appears to be forbidden with the reputation-score I currently have.) 321