William James, the American philosopher and psychologist, was born in New York City to Mary Robertson Walsh James and Henry James Sr., the eccentric Swedenborgian theologian. James's paternal grandfather and namesake was an Irishman of Calvinist persuasion who immigrated to the United States in 1798 and became very rich through felicitous investment in the Erie Canal. James had three brothers and a sister; one of them, the novelist Henry James, achieved equal fame.

James's early environment was propitious; his father's enthusiastic and unconventional scholarship, his personal and unorthodox religion, his literary association with men like Oliver Wendell Holmes Sr. and Ralph Waldo Emerson all stimulated free intellectual growth. Even more important was the rather extraordinary respect that the elder James lavished upon the youthful spontaneities of his children; each, he thought, must go his own way and become that most valuable of creatures, himself. There...