Linguist. Born in Bialystok, he practiced medicine in Warsaw. Intent on solving the problem of national conflicts, he thought that a simple international language might hasten the solution. He created an auxiliary language called Esperanto (literally, hopeful). Esperanto, which brought its creator world fame, uses all the letters of the Roman alphabet, except Q, W, X, and Y. It is spelled as pronounced, its rules have no exceptions, and its guiding principle is to use roots common to the main languages of Europe. More than 10,000 publications have appeared in Esperanto; more than 100 Esperanto periodicals are regularly published.

While Esperanto did not become a recognized and widely-used international language, it continues to have thousands of devoted followers around the world who continue to pursue cultural and organizational activities.