Towards the end of 1951, at the time when most of the institutional changes just described had already been accomplished, there appeared the first number of Myśl Filozoficzna, introduced in its editorial as a "clearly Marxist' publication. This description turned out to be perfectly true. Myśl Filozoficzna never published articles which either questioned the established Marxist- Leninist assumptions, or made a critical evaluation of them from without, or put forward opinions incompatible with the tenets of Marxism-Leninism. Practically the only deviation from this rule was some infrequent contributions on neutral subjects, and some authorised or unauthorised revisions in the interpretation of the Marxist-Leninist principles, whose validity remained unquestioned. The latter started appearing towards the end of 1955 and were the first symptoms of the forthcoming basic change, i.e., of the abolition of the "monopoly of a single school'. There would have been nothing unusual in the fact of Myśl Filozoficzna being a purely Marxist-Leninist publication, if for six years it were not the only Polish philosophical periodical.