Contemporary inscription in german
Edition: [434.bis.446 Tausend]

Wikipedia:
Walter Flex (6 July 1887 – 16 October 1917) was a German author responsible for Wanderer zwischen beiden Welten (The Wanderer between Two Worlds), a stunning war novel dealing with themes of humanity, friendship, and suffering during World War I.His Wanderer zwischen beiden Welten was published in 1916, by Beck's Verlag, and was well received. By 1917, over 700,000 copies had been printed in Germany—a testament to his extreme popularity with the wartime public[3] His reputation grew in the post-war years and his romantic idealism was exploited by the Nazi party, which found his evocative and romantic lyricism especially appealing and considered it an expression of Aryan ideals. During the time of (and partly due to) the German student movement, his reputation faded almost entirely.

He served as a soldier from 1914, having enlisted as volunteer at the outbreak of war, was injured in action and died on October 16, 1917 at Oti Manor, Saaremaa, Estonia.