It is likely that most customers of both printers and booksellers could have read textual signs (although their servants might not), but these conspicuous carved figures were especially useful before buildings were numbered. Addresses could be given as, for example, 'at the sign of the printer's devil'. The carving was also an advertisement and a way of catching the pedestrian's eye, just as barber's poles continue to be today.
It is likely that most customers of both printers and booksellers could have read textual signs (although their servants might not), but these conspicuous carved figures were especially useful before buildings were numbered. Addresses could be given as, for example, 'at the sign of the printer's devil'. The carving was also an advertisement and a way of catching the pedestrian's eye, just as barber's poles continue to be today.