This year marks what would have been the 100th birthday of Tove Jansson, one of the most successful children's writers ever. The Finnish artist is the creator of the popular Moomin book series, which follows a group of fairly tale-esque hippopotamus creatures through their adventures in and around Moominvalley. Since the first book was published in 1945, more than 15 million Moomin books have been sold around the world and they have been translated into 44 languages, but readers probably don't know just how much of of her own life Jansson put into those pudgy characters. BBC News looks into Jansson's life and how beloved characters like Moomintroll and Sniff were inspired by things like World War II, the philosopher Immanuel Kant, and the artist's secret love affair with a married woman. Read the full story on BBC News to learn how the series taught people to appreciate the small things in life, and what exactly is "the content" that lies in Thingumy and Bob's mysterious suitcase.