Before 1854 when George Boole published The Laws of Thought, the subject of logic in the western world was entirely restricted to the study of the Aristotelian syllogism, which was as old as 384-322 BC. In this work, Boole introduces a sort of algebra of propositions with probability. Booles logic forms the basis for present day Boolean Algebra, which in turn lies at the base of computer science. Because Boole is essentially inventing a number of new concepts, the discussions concerning his ideas of logic are both accessible to the non-specialist and fascinating for the historian or philosopher of mathematics and logic.