Principles of Economics[1] is a leading political economy or economics textbook of Alfred Marshall (1842–1924), first published in 1890.[2][3] It was the standard text for generations of economics students. Called his magnum opus,[4] it ran to eight editions by 1920.[5] A ninth (variorum) edition was published in 1961, edited in 2 volumes by C. W. Guillebaud.[6]