Malala Yousafzai was at an education summit in Oslo yesterday.

“If the world leaders decide to take one week and a day off from war and weapons, we can put every child in school,” Yousafzai told the Oslo Summit on Education for Development on Tuesday. “Books are a better investment in our future than bullets. Books, not bullets, will pave the path towards peace and prosperity.”

Yousafzai echoed the sentiment in a post on her Malala Fund Blog, urging people to use social media to advance her message of peace and education. “Post a photo of yourself holding up your favorite book now and share why YOU choose #booksnotbullets – and why world leaders should, too,” she wrote.

The activist got the ball rolling on the hashtag with a post on Instagram, featuring a picture of her holding a copy of Anne Frank’s “The Diary of a Young Girl.” Yousafzai wrote she chose the book “because the book reveals the courage and strength of a young girl living under war and conflict. It inspires me to believe that every child deserves the right to dream, the right to learn and the right to live in peace.”

I don’t have a single favorite book (by which I mean I have many, not that I have zero favorites). I’ll have to think about which one to brandish.