Clean slate

A clean slate, as in having ‘wiped the slate clean’, is a metaphor for a fresh, new beginning. There are two equally valid contenders for the origin. The first would be classrooms in schools where slates or blackboards would be wiped clean in order to start new lessons. The second would be taverns where records of money owed for food and drinks would be recorded on slates. Once patrons had wiped the slate clean by paying what they owed, they would be encouraged to ‘keep the slate clean’ or ‘keep a clean slate’. These last two expressions are more supportive of the tavern origin because schoolchildren would hardly be encouraged to ‘keep the slate clean’. All these figurative ‘clean slate’ expressions, whether from taverns or classrooms, date from the mid-19th century.