Brother of novelist Henry James and godson of eminent philosopher, essayist and poet Ralph Waldo Emerson, William James earned his own reputation for the monumental contributions he made in the field of Psychology. Here is the first volume of James' two part "Principles of Psychology," a textbook which took James twelve years to complete, and which is still prevalent in contemporary psychology texts. James' writings were influenced by Charles Darwin's ideas about adaptive evolutionary change, philosophical pragmatism, and various German psychologists who focused on the study of psychological processes. These two volumes delve into James' assumption that developmental processes involve an interaction of nature and nurture, a view that almost all contemporary developmental psychologists hold. His fundamental theories on brain processes and abstract thought, behavioral tendencies and states of consciousness, all of which he presented a decade before Sigmund Freud, have become integral to the framework of modern social psychology.