Gershon Levitsky has a reputation of being an outstanding physicist, dealing with the complex secrets and dynamics of gases while developing optimal consumables at a hi-tech company in Jerusalem - but who would have ever imagined that this soft-spoken man had such a fiery and secretive past? Over the last week, as millions of Jews observed Pessah all over the world, "Gershon" - as he is known to friends and colleagues - celebrated his own exodus from the former Soviet Union 21 years ago. Today, Gershon, 63, works at Oridion - a global medical devices company specializing in respiratory patient safety monitoring aimed at saving people's lives. The firm develops medical devices and patient interfaces for the enhancement of patient safety through the monitoring of the carbon dioxide in a patient's breath. Few of his associates know, however, that Gershon - a former Moscovite - once played a crucial role in a clandestine underground organization after continuously being denied permission to leave the Soviet Union during the Communist era. "I had submitted my application several times since 1979, but was refused each time," he says. In the early 70's, he secretly met with people connected to the aliya movement and received information and literature from the former generation of refuseniks. This strengthened his realization of the importance of being a Jew and the need to immigrate to the Jewish state. In 1977, Gershon, a young and inspiring physicist and researcher in medicine and biology, left the Medical Devices Division of the secret institute he was working for in Moscow, and began working at the Tuberculosis Institute. A physicist who held two patents and authored numerous scientific articles in the field of extracorporeal circulation and age physiology, he encountered a series of hardships after announcing his intention to leave Russia - including being fired more than once. Strict restrictions on religious education and freedom of expression prevented Gershon from engaging in Jewish cultural and religious activities. Understanding that the process of immigration may take a long time, Gershon says that as a refusenik, he "didn't waste a minute." He studied Hebrew, Torah and even taught karate, which was especially helpful for Jews tackling KGB street provocations. In his free time, Gershon would listen to the Voice of America and Kol Yisrael with a special short-wave radio he had purchased. In the course of his seemingly endless wait for an exit visa, Gershon never lost hope, and became one of the key pillars of the underground organization, despite Communist restrictions. Gershon was a member of the Samizdat - the secret copying and distributing of government-restricted material. Within the framework of his Samizdat activities, Gershon served as the "minister of communications" of the Moscow underground and was in-charge of 35 people. Since Soviet censorship had to approve every document - even those favorable to the regime - Gershon and his friends engaged in surreptitious printing and publication of Hebrew literature and dictionaries as well as Jewish and Zionist books - including Leon Uris's Exodus. Finally, in 1988 at the age of 42, Gershon managed to get out of Russia and immigrate to Israel with his wife and son. He is still in touch with members of the former underground. Once a year, they hold a picnic, along with their families. After 15 years at Oridion, Gershon, along with his co-workers, has nine patents in the field of patient interfaces issued under his name. While physics analyzes nature to comprehend how the world and universe function, Gershon says his unique experience has taught him the true meaning of life. "The main reason for my making aliya was Jewish pride," he says. "That's what I was looking for." The writer works as a marketing communications specialist at Oridion.