Of crucial importance in understanding how Pascal moved from his geometrical studies to his investigations concerning man and God is 'De l'esprit geometrique et de l'art de persuader' - 'On the Geometrical Mind and the Art of Persuasion.' The date of composition, although uncertain, is usually given as around 1658. The tone of the short monograph is magisterial and precise; one senses that Pascal had in mind certain pupils for whom he was writing. We know that at about the same time Pascal had written a Preface for an essay on the elements of geometry for the Petites Ecoles de Port-Royal. Given that Pascal always had a clear idea of the audience he was attempting to reach, we can safely assume that he had the puils of Port-Royal in mind.