Since 1939 he has been a member of the Workers' Youth League and became a participant in the underground communist movement.[1] After the September 1944 coup d'état, Mateev began working as a journalist and soon entered the government of Bulgaria.[2] In 1950, Mateev received the title of professor, and in 1967 an academician of the Bulgarian Academy of Sciences.In his honor, an auditorium in the University of National and World Economy bears his name.According to him, the proponents of market socialism offer in practice a return to "idealized capitalism, and that of the age of free competition."