(CNN)After Barbara Bush's funeral, everyone was talking about the photo.
No, not that photo -- of the four ex-presidents, three former first ladies and current first lady Melania Trump -- that made the rounds on social media over the weekend.
The other much-talked about picture was a photo of the socks worn at the funeral by former President George H.W. Bush, who is known for wearing bold, patterned socks.
The photo is a close-up of Bush's ankles, adorned with black socks decorated with a stack of blue, red and yellow books. It's a nod to Barbara Bush's main cause during her White House years: literacy.
Motivated by her son Neil's dyslexia, she chose family literacy as her main cause while first lady.
In 1991 she helped pass the National Literacy Act, which focused on teaching millions of American adults to read.
She also founded the Barbara Bush Foundation for Family Literacy, a charity that encourages reading and writing in low-income households. Since 1989, the foundation has partnered with local organizations and raised more than $110 million to create and expand literacy programs across the country.