Volumes 7 and 8 comprise Mill's landmark philosophical work 'A System of Logic, Ratiocinative and Inductive', in which Mill explores the basic principles of inductive reasoning. In this work Mill presents the five basic modes of induction, which are now known as Mill's Methods: the method of agreement, the method of difference, the joint or double method of agreement, the method of residues, and that of concomitant variations. In contrast to Aristotle's syllogisms, which are based on deductive reasoning, Logic provides an alternate path to knowledge and constitutes an important contribution to the development of the scientific method.