Two books belonging to scientist Charles Darwin that had been missing for over 20 years were returned to the Cambridge University Library, UK. While carrying out research to understand how different animals evolved over time, Darwin recorded his ideas and learnings in a series of notebooks, which were labelled with the letters of the alphabet. These learnings of Darwin were then converted into a book. The two books, worth millions of dollars, went missing in 2001 when they were being photographed. The books were anonymously returned to the library in a pink gift bag along with a note wishing the librarian, ‘A Happy Easter’.