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A commonplace book is a personal repository of quotes, recipes, formulas and ideas organized by subject rather than by date. The term comes from the Latin locus communis and the Greek topos koinos, and in the classical world Aristotle, Cicero and Quintilian used commonplaces as mental frameworks for rhetoric. Seneca the Younger told readers to gather ideas the way a bee gathers pollen, and in the fifth century Stobaeus excerpted more than 1,400 works into his Anthologies, preserving fragments of 315 texts that are otherwise lost. Medieval preachers built florilegia, or gatherings of flowers, and 15th century Italian merchants kept zibaldoni that mixed tax records and exchange rates with poetry from Dante.

After the printing press flooded Europe with books, Oxford and Harvard taught commonplacing, and Erasmus traveled with a wooden chest of notes. In 1685 John Locke published a method that indexed entries in a grid of letters and vowels, and publishers such as John Bell later sold blank books with the grid preprinted. Erasmus Darwin filled one from 1776 to 1787, and his grandson Charles Darwin called it the Great Book. Carl Linnaeus moved his notes onto loose slips he could rearrange, and W. Ross Ashby kept 25 volumes and more than 7,000 pages over 44 years.

• Giovanni Rucellai described his hodgepodge book as a salad of many herbs.
• Locke’s index filed a quote on courage under the C and O box, letting notes be written in any order without wasted pages.
• Elizabeth Lyttelton kept her books from the 1670s to the 1710s, and Anna Jameson used hers as a self-directed syllabus.
• Ronald Reagan stored jokes and anecdotes on index cards inside the plastic sleeves of black photo albums.
• Amos Bronson Alcott observed in 1877 how heavily authors depend on their diaries and commonplaces.