In GC II 2, Aristotle discovers the contrarieties that constitute the principles of all perceptible bodies. They are the hot and the cold, the dry and the moist because they are the basic tangible contrarieties that interact as active and passive powers in a way that can result in a new affection. In GC II 2, Aristotle also attempts a reduction of all other tangible contrarieties to the basic four. I argue that the active/passive relation does not hold only between the two basic pairs of contrarieties but also within each pair. I compare the reduction of other contraries to the basic four with what Aristotle says in Meteor. IV. Despite minor differences and the wider scope of analysis in the latter work, Aristotle’s admirable effort to reduce the rich variety of tangible properties to a limited number of contraries and elements is the same.