Logical works of this period, beginning with Generales Inquisitiones and ending wi th the two dated pieces of 1 Aug. 1690 and 2 Aug. 1690 , are read as a sustained effort, finally successful, to develop a set of axioms and an appropriate schema for the expression of categorical propositions faithful to traditional syllogistic. This same set of axioms is shown to be comprehensive of the propositional calculus of Principia Mathematica, providing that ‘Some A is A’ is not a thesis (...) in an unrestricted sense. There is no indication in the works of this period that Leibniz understood just how significant is this logicalsystem he developed. But it is undeniable that he held tenaciously to this particular set of axioms throughout the period, a set of axioms of great power. (shrink)