Abstract Leibniz was the last schoolman and the first modern logician .He invented different types of formalization of Aristotelian logic which in parts anticipated George Boole's calculus .But the logic of Leibniz is assuredly that part of his system that has been most neglected by historians of philosophy and mathematics .Philosophers,understandably seduced by his metaphysics,have accorded little form it assumed .Mathematicians,on the other hand,have looked to Leibniz primarily as the inventor of the differential and integral calculus and have been engaged neither by his general theories on the value and importance of the mathematical method nor by his attempts at applying algebra to logic,which they have contemptuously dismissed as metaphysics .As a result,neither group has fully grasped the principles of his system,nor have they been able to reach the source from which both the infinitesimal calculus and the Monadology flow . There is,of course,the excuse that Leibniz's logical essays have been published only slowly and very incompletely .Even today they are scattered piecemeal among various partial editions,most notably the two in s which Gerhardt has so unfortunately separated the mathematical and philosophical writings . As if one could dissect the work of an encyclopedic savant whose philosophy was nourished by the study of all the sciences and in turn inspired all of his scientific discoveries .If there is a thinker whose thought cannot be divided with impunity in this way,it is certainly the one who said :″My metaphysics is entirely mathematical,″or again,″Mathematicians have as much need to be philosophers as philosophers have to be mathematicians .″This artificial and arbitrary division between contemporaneous works that mutually depend on and illuminate one another has had the result of concealing the unity of the system and of hiding its true principles . Thus the absurd and deplorable schism between letters and sciences not only compromises the future of philosophy,but also falsifies its history and renders its past unintelligible by isolating it from the scientific speculations where it has always taken root .One sees readily that Leibniz's philosophy was bound to suffer more than any other,and within this philosophy his logic,precisely because it is the center of,and the link between,his metaphysical speculations and his mathematical inventions .
