Because religion offered possibilities for thought and activities independent of the state, it too was severely restricted and controlled. Clergymen were required to be licensed. In attempting to manipulate the number and kind of clergy, the state even sponsored a pro-government organization of Catholic priests, the Association of Catholic Clergy Pacem in Terris. Nevertheless, there was religious opposition, including a lively Catholic samizdat. In the 1980s, František Cardinal Tomášek, the Czech primate, adopted a more independent stand. In 1984 he invited the Pope to come to Czechoslovakia for the 1,100th anniversary of the death of Saint Methodius, the missionary to the Slavs. The pope accepted, but the trip was blocked by the government. The cardinal's invitation and the pope's acceptance were widely circulated in samizdat. A petition requesting the government to permit the papal visit had 17,000 signatories. The Catholic Church did have a massive commemoration of the 1,100th anniversary in 1985. At Velehrad (allegedly the site of Methodius's tomb) more than 150,000 pilgrims attended a commemorative mass, and another 100,000 came to a ceremony at Levoca (in eastern Slovakia).