The Algebra of Logic

Mathematical Logic is a necessary preliminary to logical Mathematics. _Mathematical Logic_ is the name given by Peano to what is also known (after Venn ) as _Symbolic Logic_; and Symbolic Logic is, in essentials, the Logic of Aristotle, given new life and power by being dressed up in the wonderful_ almost magical_armour and accoutrements of Algebra. In less than seventy years, logic, to use an expression of De Morgan's, has so thriven upon symbols and, in consequence, so grown and altered that the ancient logicians would not recognize it, and many old-fashioned logicians will not recognize it. The metaphor is not quite correct: Logic has neither grown nor altered, but we now see more of it and more into it.