In 1904, Hitler had become seriously ill and bedridden due to a lung ailment. He even had to leave school and stay home sick. Once there, his family doctor Eduard Bloch, a Jewish-Austrian practicing in Linz, fixed him up. 

When Hitler’s mother was diagnosed with breast cancer in 1907, Bloch tended to her as well, until she passed away on the December of that year. Due to their poor economic circumstance, Bloch had worked for the Hitler family for reduced prices, and sometimes didn't even take any money at all. 

For his generosity, an 18-year-old Hitler granted Blouch his “everlasting gratitude.” At the time, Bloch probably didn’t realize how powerful Hitler’s “gratitude” would come to be. 

In 1908, Hitler could only express it by sending Bloch hand-made gifts. But in 1937, he personally ensured that Bloch would never be sent to a concentration camp, and had him and his family protected. He referred to Bloch as the “noble Jew.”