Franz Kafka (3 July 1883 – 3 June 1924) was a German-language writer of novels and short stories, regarded by critics as one of the most influential authors of the 20th century. Kafka strongly influenced genres such as existentialism. Most of his works, such as "Die Verwandlung" ("The Metamorphosis"), "Der Prozess" ("The Trial"), and "Das Schloss" ("The Castle"), are filled with the themes and archetypes of alienation, physical and psychological brutality, parent–child conflict, characters on a terrifying quest, labyrinths of bureaucracy, and mystical transformations. Kafka was born into a middle-class, German-speaking Jewish family in Prague, then part of the Austro-Hungarian Empire. In his lifetime, most of the population of Prague spoke Czech, and the division between Czech- and German-speaking people was a tangible reality, as both groups were strengthening their national identity. The Jewish community often found itself in between the two sentiments, naturally raising questions about a place to which one belongs. Kafka himself was fluent in both languages, considering German his mother tongue. Kafka trained as a lawyer and, after completing his legal education, obtained employment with an insurance company. He began to write short stories in his spare time. For the rest of his life, he complained about the little time he had to devote to what he came to regard as his calling. He regretted having to devote so much attention to his "Brotberuf" ("day job", literally "bread job"). Kafka preferred to communicate by letter; he wrote hundreds of letters to family and close female friends, including his father, his fiancée Felice Bauer, and his youngest sister Ottla. He had a complicated and troubled relationship with his father that had a major effect on his writing. He also suffered conflict over being Jewish, feeling that it had little to do with him, although critics argue that it influenced his writing.