Janusz Korczak, the pen name of Henryk Goldszmit (1878 or 1879–1942), was a paediatrician, writer, pedagogue and Polish Jew, known as Pan Doktor (Mr. Doctor) or Stary Doktor (Old Doctor). Determined to shield children from the injustices of the adult world he introduced progressive orphanages, serving both Jewish and Polish children in Warsaw. He is the author of over 20 books including How to Love a Child, The Rules of Life, King Matt the First and Kaytek the Wizard, and over 1,400 articles. He refused offers for his own safety repeatedly and stayed with his orphans when the entire population of the institution was sent from the Ghetto to the Treblinka extermination camp, during the Grossaktion Warsaw of 1942.