Ima Hogg (1882-1975) was good at keeping secrets. After lo, these many years, hers are still safe. 

Here's an excerpt from Grand Tours and the Great War: Ima Hogg's Diaries, 1907-1918:  

 Here, on the last day of February 1908 (February 29, a Leap Year), Ima Hogg’s Berlin diary, which she began on January 1, ends abruptly. The little black leather book in with its brass lock has many unused pages.

         Why did she suddenly stop keeping a diary? She lived at 22 Mommsenstrasse (except for part of the summer) until October 1908, when she sailed for home.

         What did she do from March to October? Surviving documents are few: 

         On March 9 and 13 she went to concerts at two of her favorite venues in Berlin: “Mozart Saal,” March 9; “Philharmonie,” March 13.  There are programs with these dates in her scrapbook, but she did not record who, if anyone, accompanied her.