108 years ago today, on April 14, 1917 (February 23, 1917, the lunar calendar), Dr. Zamenhof, founder of Esperanto and Polish internist and ophthalmologist, passed away. Razaru Ludwik Zamenhof (December 15, 1859-April 14, 1917, Polish Jew, founder of Esperanto. When he was born, Poland was under the rule of Tsar Russia. According to Russian household registration regulations, he was named Razaru Markovic Zamenhof (plus his father's name). However, after Poland's independence, according to the regulations of the new government, although he was Jewish, he had to add a Christian name, so the name on his ID card changed to Razaru Ludwik Zamenhof. Zamenhof's mother tongue was Russian and Yiddish, but he was also proficient in Polish and German. He later learned French, Latin, Greek, English and Hebrew, and also studied Italian, Spanish and Lithuania. The town where he was born was inhabited by people of three ethnic groups: Poles, Jews and Belarusians. Due to different languages and different religious beliefs, they often have prejudice and hatred against each other. Zamenhof believed that different languages and inability to communicate with each other was the main reason for prejudice. When he was still in middle school in Warsaw, he tried to create a common language for mankind so that people of different ethnic groups could communicate with each other well. Later, he went to Moscow and Warsaw to study medicine. After graduation, he became an ophthalmologist. During the course of practicing medicine, he had been learning foreign languages and devoted himself to continuing to study international languages. It was not until 1887 that with the support of his future father-in-law, he was able to publish his research results: "International Languages" under the pseudonym "Doctor Hope." The word "Doctor Hope" in Esperanto is "Doktoro Esperanto", and Esperanto became the customary name of Esperanto. Esperanto became Zamenhof's hope to realize his ideals of peace and exchanges between different cultures. Esperanto is mainly based on the words of the Germanic and Latin languages of the Indo-European family. It simplifies the grammar as much as possible to make the written text and pronunciation completely consistent with each other. Therefore, it is easy to learn and has become the most successful artificial language in the world. There are Esperanto groups in many countries around the world.