The photo has since racked up hundreds of reactions and shares, thanks in part to a posting in Pantsuit Nation, the private Facebook group started by Hillary Clinton supporters.

Threefoot told Refinery29 that while she was "completely overwhelmed by the response" to the photo, she wasn't surprised by the response her daughter had to Ginsburg and her story.

When she discovered Dissent at a writing conference, Threefoot knew it was going to be a hit at home.

"She has been dissenting and disagreeing since the day she was born. :-) The fact that [the book] was about RBG only made it more perfect," she wrote in an email.

Michele has already read the book at least 10 times on her own, her mother said. Michele "was especially struck" by Ginsburg's support for the Fair Pay Act; the young activist had participated with a friend in a mock protest for "equal pay for equal work" as part of a Girl Scout activity. "That struck home," Threefoot said.

Threefoot said she's tried to convey to her daughter that a lot of people have seen and loved her photo, "because they believe in the same things we do, like kindness, justice, and equality, and because they also admire Justice Ginsburg for fighting for those things."

And perhaps more importantly, said she hopes the popularity of the post inspires more people to share the book — and Ginsburg's story — with young girls in their lives.

"It's written in a way that makes Justice Ginsburg very identifiable for kids, and, more importantly, makes it clear how one girl who firmly rejects injustice even on the smallest scale can grow up to be someone who changes the world," she said. "My daughter now refers to her as Ruth, like she's a friend of hers, and has taken the message the book conveys to heart."

Editor's note: This post has been updated to clarify that Michele participated in the equal pay mock protest before learning about Ginsburg's legacy.