According to Lewis, Native American informants told him that, "the snake was built in commemoration of a Great War speech made by a Dakota chief at a time when the tribe had just returned from a grand hunt in they had been very successful."
Famed Dakota writer, historian and activist, Vine Deloria Jr., chronicled a familial connection to the site in his book, Singing for a Spirit, part of which is a both a metaphysical and historical account of the life of his great-grandfather, a Yankton Dakota chief named Saswe.
In the book, a young Saswe hears voices calling him to embark on a vision quest.
"They ended up camping at the Medicine Knoll, and he went up there to have his vision," recalls Dr. Phil Deloria, Harvard University Professor of History and son of Vine Deloria Jr., great-great-grandson of Saswe. "The way my grandfather was told it, was that you could do a vision by standing, praying with the pipe, or you could do a vision in a somewhat different way, by digging a kind of a hole, with a kind of a little seat in it, and then you would put your head down and you would wait."
According to the account recorded by his father, Saswe's vision presents him with a choice of two roads. Either choice will lead to a complex set of consequences. Meanwhile, as Saswe is engaged with these decisions, a dramatic tableau unfolds on Medicine Knoll.
"His cousin, Brown Bear, was sent up to check on him, to check on Saswe," says Deloria. "And Brown Bear rode his horse up, up the Medicine Knoll, and was stopped by all of these rattlesnakes. And the snakes would not let him pass. And [it was] very, very traumatic I think to sort of imagine that these snakes... but you feel like you have to go, and couldn't quite get there but he got to the point where he could see Saswe."
From Singing for a Spirit: "Brown Bear was determined to see what had happened to his cousin. Using his rope, he lashed at the snakes and opened a path and rode several hundred feet forward to see if he could locate Saswe. There in the distance he saw a large bundle of snakes furiously writhing back and forth over Saswe's prostrate body."
Distraught, Brown Bear descends from Medicine Knoll with the news. The camp begins to mourn inconsolably, in a customary fashion.
"And at that point," says Deloria, "Saswe — in the middle of this mourning practice — Saswe came down off the hill. And there he was."
Today, one can still see the indentation in the earth, near the head of the effigy, where Saswe is reputed to have been covered with snakes.
Vine Deloria Jr. did not make an explicit connection between Saswe's ordeal and the effigy, though he did mention the latter, almost in passing. "On the southern part of that butte," he wrote, "in the old days, there was a long and twisting trail of rocks arranged to resemble a rattlesnake... When my father and I walked the butte in 1986, he remarked that he was happy it was a cold October day and we would not meet any snakes. I was standing behind him looking at several garter snakes and praying that we wouldn't encounter a rattler."
"When we get the story, we don't really know what kind of planning went into that," Phil Deloria explains. "But one could imagine: 'Why that one? Why not a different one?' The way my dad tells the story, they just happened to be heading North, and as I recall, he says then they broke off from the main group and they went over to this place. And so they went there with intention that Saswe could do a vision quest.
"So they knew where they were going. And they went there with some purpose. So was the purpose... that's a place that people go to have visions? Or was it even more specific, backed up by a larger set of knowledge than that? Like, that's a place people have snake visions, rattlesnake visions? It feels to me entirely possible to imagine a great depth of knowledge that's sort of lost to us as we tell the story."
Dr. Craig Howe of the Center for American Indian Research and Native Studies has studied stone effigies.
"Another thing about these effigies out of rocks... rocks are not just rocks in Lakota cosmology," says Howe. "This idea of these rocks are, from their origins, from the beginning of time from a Lakota perspective. This is a being... this is... how to say that?
"These rocks are evidence of an original being called Inyan. And he was what was here at the beginning. And eventually, Inyan, which I just love the phrase, he pulsated with the potentiality of the universe. So this being eventually, through processes that are in Lakota cosmology, he bled out, and went from this amorphous powerful being to this hard, brittle substance that we call rock today.
"So any of these rocks are, in Lakota cosmology they're referencing Inyan, that original being. So, to use them to make a shape of anything can have these really strong cultural significance."
"The people on this landscape knew this landscape cold," says Deloria. "They knew everything about it. They traveled all over it. They understood it in great detail. And these kinds of places, these Medicine Knolls and buttes, this feels to me like something that was knowledge that was held collectively by people, for a really long time."