"The various systems of doctrine that have held dominion over man have been demonstrated to be true beyond all question by rationalists of such power-to name only a few-as Aquinas and Calvin and Hegel and Marx. Guided by these master hands the intellect has shown itself more deadly than cholera or bubonic plague and far more cruel. The incompatibility with one another of all the great systems of doctrine might surely be have expected to provoke some curiosity about their nature."