Scottish mathematician John Napier (1550–1617) first had the idea about logarithms in 1594. It took him twenty years, until 1614, to publish a canon of logarithms called Mirifici logarithmorum canonis descripto (Description of the wonderful canon of logarithms). The canon explains the nature of logarithms, gives their rules of use, and offers logarithmic tables. (For more about logarithms, see “Algebra.”)