The decoration of Gothic iron locks and keys was often elaborate and of the highest standard of workmanship. The motifs were frequently drawn from Gothic architecture, reproducing on a miniature scale complicated tracery patterns and even tiny statuettes. A number of these tiny locks were compound, with some of the mechanisms concealed from view, and required two or even three keys used in sequence to open them. It has been suggested that the greatly expanded use of locks on doors, or coffrets and other types of storage chests was a result of the increasing urbanization of life and the new emphasis on material wealth and private ownership which developed in the late Middle Ages.