There is a note in the documents of the Russian secret service about Zamenhof that describes denunciation letters to the Tsar's officers.
One anonymous denunciation concerned the arrival in Białystok of a Hebrew teacher from Warsaw, Bernard Wildenbaum, who was charged due to usage of Polish national dresses.
[2] If he taught in that high school, probably that was only a short episode after many Polish teachers were dismissed in reprisal after the January Uprising of 1864.
The censorship "mistake" of Zamenhof was presented as important cause of the financial problems of the family that prompted his migration to Grodno in October 1893.
In the 1890s three of his sons started their costly university education: Fabian — pharmacology, Grzegorz (Henriko) and Leon — medicine.