A year ago, Sergio Pereira, my friend and teacher, left our world. He was a true patriot of Ukraine, an honest and brave man. He loved to repeat a phrase from the novel “Moby Dick” by Herman Melville: I love to sail forbidden seas, and land on barbarous coasts. He often, following the example of the heroes of Vasily Zvyagintsev, called himself, either jokingly or seriously, an explorer, and laughed merrily when I wanted to correct him. Let this book be a sign of my admiration for his attitude towards life, work and the world around him. Happy sailing on the waves of Eternity, dear friend!