Just about 1625 years ago, during the Roman Emperor Flavius Theodosius Augustus, or Theodosius the Great, the Roman general Publius Flavius Vegetius Renatus, around 394, wrote in Latin the book Epitoma Rei Militaris or De re militari (Concerning Military Matters), in which he mentions Igitur qui desiderat pacem, praeparet bellum , later simplified as Si vis pacem, para bellum , which means If you want peace, prepare for war .Well, after over 1625 years of wars after wars after wars, the over 7.7 billions of people on Earth demand a change: Si vis pacem, para PACEM! No need to translate, but if you insist: If you want peace, prepare for PEACE!On 24 November 2019 Pope Francis called for a ‘world without nuclear weapons’ during his Nagasaki visit.Using a lovely imaginary dialog between Sun and Earth, this book is exactly what we need to really prepare for peace, with clear and practical ideas, which will help the over 7.7 B people to have a Harmonious World, with Sustainable Peace, Freedom, Health, Friendship and Prosperity.