29. Formula concerning the Guard at the Gates of a City.

De Custodiendis Portis Civitatis.

'We entrust to you an important office, the care of the gate of such and such a city. Do not keep it always shut—that were to turn the city into a prison; nor let it always lie open—then the walls are useless. Use your own judgment, but remember that the gate of a city is like the jaws of the human body, through which provisions enter to nourish it.'