Think about it... Your great grandpa who lived centuries ago and who is still known for the great inventions that he made in the past wrote you a letter! Ibn Sina the sultan of doctors, Katip Chelebi the important historian and geographer, Sinan the great architect, Rumi the famous poet and author, Piri Reis the first navigator who drew a world map and Yunus Emre the poet who captured everyone's hearts with his poems wrote you a very special letter. It is very exciting, isn't it? When you read these letters, you will both travel to the times your grandpas lived in and learn about their wonderful works. Come on, kids! Now it is time to read the letters from our "Wise Grandpas"...