In the very first story to feature the loveable amphibian, Frog is feeling most unwell. He keeps getting hot, then cold, and something inside his chest is going 'thump, thump'. Hare says it means he's in love! But who with? And how can he show his devotion - perhaps by performing the biggest jump ever?
Born in The Hague in 1923, Max Velthuijs is now considered to have been one of Holland's most important creators of children's books, alongside Dick Bruna. Max won many awards, including the highly prestigious Hans Christian Andersen Medal in 2004. He died in 2005, aged 81.