The second reason for which this book is stupendous is the egregious, stupendously BAD self-insertion of the narrator. Leland wants to portray himself as a learned authority on the "red man," so he goes to laughable lengths to trot out his intellectual achievements. His "achievements," such as they are, consist basically in very strained comparisons between the Abenaki mythos and either the Norse mythos or the Finnish mythos.  I'm all for investigating the influence of certain myths on others and the spread of certain story tropes and what this might say about the modes of thinking common to all cultures [we've all got dragons, vampires, half-human, half-fish water creatures, were-animals, etc., etc., etc.]. However, Leland is less interested in universal mythic themes than he is in proving the Abenaki mythos a poor derivative of the great European traditions. We see Leland's Angoclentric bias most clearly in his comment about Glooskap, a kind of Trickster/Creator/demi-god/buffoon/cultural hero:

Glooskap…is by far the grandest and most Aryan-like character ever evolved from a savage mind and…is more congenial to a reader of Shakespeare and Rabelais than any deity ever imagined out of Europe… (p. 2 of the introduction)

Leland clearly assumes that the Abenaki people are "savages," that is, mentally deficient and unable to attain the literary heights represented by Shakespeare and Rabelais. The supposedly primitive corpus of Abenaki stories produces only one character that measures up to "Aryan-like" standards of grandeur. All the other characters are pathetic stereotypes. It's screamingly obvious from Leland's comment that the observer cannot be separated from the perspective, i.e., that his basis for comparison is Shakespeare and Rabelais because that's all he knows. It is possible to try to look at a mythos on its own terms, i.e., how it talks to itself, to the people, to the world around it, but Leland only wants to use the Abenaki stories to learn about himself. The Abenaki stories serve his preconceived conclusion that the "Aryan" culture [= white western European] is the most civilized, advanced and intelligent ever and everyone else is just a shoddy knock-off.

Heck, Leland even admits that he went into this story-collecting project with expectations of finding inferior stories. He says in the preface (p. 1):

When I began, in the summer of 1882, to collect among the Passamaquoddy Indians at Campobello, New Brunswick, their traditions and folklore, I expected to find very little indeed. These Indians, few in number, surrounded by white people and thoroughly converted to Roman Catholicism, promised but scanty remains of heathenism. What was my amazement, however, at discovering, day by day, that there existed among them, entirely by oral tradition, a far grander mythology than that which has been made known to us either by the Chippewa or the Iriquois Hiawatha legends, and that this was illustrated by an incredible number of tales.

In other words, he thought that the Passamaquoddy community had had all their native blood bleached and beaten out of them, taking the stories with them as it spilled into the earth. Upon "discovering" that the Passamaquoddy perpetuated their culture, tradition, religion and stories, Leland was as stupefied as he would have been if someone had told him that women should be allowed to go to college. Despite his realization, enumerated in the title of this entry, he could not comprehend that the Passamaquoddy were people just like him and therefore continued to "prove" their inferiority by showing the degeneracy of their cultural traditions as compared to the glorious Aryan originals.

And you know — this complete blindness to one's prejudices is still be practiced right this very instant on Native Americans and anyone else dead white males think is uninteresting or unworthy of note.