This volume contains seventeen essays in the history of modern mathematical logic. The first nine are concerned with the completeness of various logical calculi. The second five essays deal with the completeness of classical first-order predicate logic. One essay deals with the history of Cantor's definition of set, another with the set-theoretical reduction of the concept of relation, and a final essay is devoted to a survey of various meanings of the concept of completeness of formalized deductive theories. The essays were first presented in the national conferences of the Thematic Group...