Objectivism is a philosophical system developed by Russian-American writer Ayn Rand (1905–1982). Rand first expressed Objectivism in her fiction, most notably The Fountainhead (1943) and Atlas Shrugged (1957), and later in nonfiction essays and books. Leonard Peikoff, a professional philosopher and Rand's designated intellectual heir, later gave it a more formal structure. Peikoff characterizes Objectivism as a "closed system" that is not subject to change.