In 1975, Jerome Saltzer and Michael Schroeder published "The Protection of Information in Computer Systems," which outlined a series of design principles for secure systems. Some principles, like separation of privilege and least privilege, have become staples of information security practice. Other principles, like simplicity and complete mediation, have failed to thrive. Attempts to codify information security principles for general practice have also failed to thrive. With a few exceptions, modern textbooks either entirely omit lists of principles or present only the 1975 list. Although such lists might provide useful, if incomplete, guidelines for practitioners, their principal value might be in teaching students the fundamental concepts of information security.