Zamenhof Day Zamenhof Day Zamenhof Day (), also called Esperanto Book Day, is celebrated on 15 December, the birthday of Esperanto creator L. L. Zamenhof. It is the most widely celebrated day in Esperanto culture. On this day, Esperantists hold information sessions and cultural gatherings to promote literature in Esperanto. The history of celebrating Esperanto on Zamenhof's birthday can be traced back to 17 December 1878, when at a birthday party for his 19th birthday he presented to his friends his "Lingwe uniwersala", the first version of his international language. By 1887, this language had evolved into what is now recognized as
Ludwik Krzywicki Ludwik Krzywicki Ludwik Krzywicki (21 August 1859 – 10 June 1941) was a Polish anthropologist, economist and sociologist. One of the early champions of sociology in Poland, he approached historical materialism from a sociological viewpoint. From 1919 to 1936 he was a professor at the University of Warsaw. Ludwik Krzywicki was born at Płock in 1859 into an aristocratic but impoverished family. From an early age he showed an interest in psychology, philosophy and natural sciences, and studied the works of Darwin, Taine, Ribot and Comte. Krzywicki studied mathematics at the University of Warsaw in Congress Poland. After obtaining his