Tadeusz Mazowiecki, Poland's first prime minister after the fall of communism, died on Monday aged 86.
Mazowiecki, who emerged from Poland's dissident intellectual tradition, was famously photographed making a victory sign after his election for prime minister, which marked the beginning of the end of 40 years of Cold War politics in Eastern Europe.
He was one of the architects of the "Round Table" talks, which brought together the Soviet-installed communist authorities and the opposition to pave the way for Poland's peaceful transition to democracy in 1989.
"Moreover, the Polish democracy is failing a little bit now and we would need him here, but it seems that he is also needed on the other side."
President Bronislaw Komorowski, speaking in the southern city of Brzeg Dolny, said: "Tadeusz Mazowiecki, with his wise and calm will, set the directions for Poland's development."
Wojciech Jaruzelski, Poland's last communist leader, also praised Mazowiecki. "I have always admired his calmness, his consciousness and his decisiveness," he told public TVP Info.
Born in 1927, Mazowiecki was behind the "thick line" concept under which lower-ranking communist-era officials could also work in the newly democratic Poland.
Some of Poland's rightist groups criticized him for this, saying his approach allowed many communist officials avoid responsibility for their wrong-doings before 1989.
As prime minister, he oversaw Poland's shock economic therapy of early 1990s aimed at replacing the centrally controlled communist economy with a free market and sought to mend ties with Poland's neighbors, such as Germany.
Mazowiecki was a Catholic activist under communism and joined the Solidarity trade union 1980 strikes in the Gdansk shipyard offering support for the protesting workers from the country's independent intellectuals.
Arrested in 1981 when the communist authorities declared martial law to crush Solidarity, he became an adviser to Walesa, the union's charismatic leader, who was later elected Poland's first post-war non-communist president in 1990.