North Whitehead Alfred: - Born on February 15, 1861, Alfred North Whitehead OM FRS FBA died on December 30, 1947. He was an English philosopher and scientist. He came up with the school of thought called "process philosophy," which has been used in many fields, such as ecology, religion, education, physics, biology, economics, and psychology. Whitehead wrote mostly about math, logic, and physics in the beginning of his work. He and Bertrand Russell, a former student, wrote the three-volume Principia Mathematica between 1910 and 1913. Modern Library ranked Principia Mathematica as the 23rd best English-language nonfiction book of the 20th century and said it was one of the most important works in mathematical reasoning written in that century. In the late 1910s and early 1920s, Whitehead slowly moved from studying mathematics to studying the philosophy of science and then to studying metaphysics. He came up with a complete metaphysical system that was very different from most Western thought. In his argument, Whitehead said that reality is made up of processes, not things, and that the best way to describe a process is by how it interacts with other processes. He disagreed with the idea that reality is made up of separate pieces of matter. Some of Whitehead's philosophical works, like Process and Reality, are seen as the foundational books of process philosophy.