with other Polish dissidents, including Stefan Amsterdamski, Andrzej Celiński and Andrzej Kijowski, became one of the founding members of the Society of Scientific Courses, the predecessor of the Flying University. Solidarity and the fall of Communism In August 1980, he headed the Board of Experts, which supported the workers from Gdańsk who were negotiating with the authorities. From 1981, he was the editor-in-chief of the Tygodnik Solidarność weekly magazine. After martial law was declared in December 1981 he was arrested and imprisoned in Strzebielnik, then in Jaworz and finally in Darłówek. He was one of the last prisoners to be released on 23 December 1982. In 1987, he spent a year abroad, during which he talked to politicians and trade union representatives. Starting in 1988, he held talks in Magdalenka. He firmly believed in the process of taking power from the ruling Polish United Workers' Party through negotiation and thus he played an active role in the Polish Round Table Talks, becoming one of the most important architects of the agreement by which partially free elections were held on 4 June 1989. While the Communists and their satellites were guaranteed a majority in the legislature, Solidarity won all of the contested seats in a historic landslide. The Communists had originally planned for Solidarity to be a junior partner in the ensuing government. However, Solidarity turned the tables on the Communists by persuading the Communists' two satellite parties to switch their support to Solidarity. This would all but force Communist President Wojciech Jaruzelski to appoint a Solidarity member as prime minister, heading the first government in 45 years that was not dominated by Communists. At a meeting on 17 August 1989, Jaruzelski finally agreed to Lech Wałęsa's demand to pick a Solidarity member as the next prime minister. Walesa chose Mazowiecki as a Solidarity candidate to lead the coming administration. On 21 August 1989 General Jaruzelski formally appointed Mazowiecki as Prime Minister-designate. On 24 August 1989, he won a vote of confidence in the Sejm. He thus became the first Polish prime minister in 43 years who was not either a Communist or a fellow traveler, as well as the first non-communist Prime Minister of an Eastern European country in over 40 years. Prime Minister On 13 September 1989 during his long investiture speech outlining the extensive political agenda of his nominated cabinet prior to the mandatory confidence vote, Mazowiecki grew