Alfred North Whitehead, OM FRS (15 February 1861-30 December 1947) was a philosopher and mathematician. He is the founding father of the philosophical school of process philosophy. This school has found many areas of application to the disciplines of ecology, theology, education, physics, biology, economics, and psychology. His early work was in logic, and physics. The three-volume Principia Mathematica (1910-13), written with Bertrand Russell is considered to be one of the most important classical works in mathematical logic. Starting late in 1910 Whitehead developed an interest in philosophy of science, and metaphysics. Whitehead's main point of departure from western philosophy is that reality was fundamentally constructed by events rather than substances which means that both are intertwined in a web of reality. Whitehead argued that "there is urgency in coming to see the world as a web of interrelated processes of which we are integral parts, so that all of our choices and actions have consequences for the world around us."