The fanciful optimism of Miguel Sánchez-Mazas. Let us calculate... = Freedom and Justice

May 2020 marks the 25 th anniversary of the death of Miguel Sanchez-Mazas, founder of  Theoria - An International Journal of Theory, History and Foundations of Science  and regarded as the person who brought mathematical logic to Spain. Here we present some of his biographical features, as well as a summary of his contributions, from his early work in the 1950s - introducing contemporary advances in logic and philosophy of science in a philosophically backward milieu dominated by the scholasticism of that era in Spain - to the development of a project of Lebnizian lineage aimed at producing an arithmetic calculation that would elude some of the difficulties confronting Leibniz's calculus.