An alternative guide to perimetry and perimeters with light-hearted pictures and a serious discussion of some concepts and definitions, including an analysis of errors in existing textbooks, manuals and standards related to perimetry. “To a foreign monastery with its own rules?!” This will probably be the reaction of most specialists to a book in which a REA designer is trying to teach ophthalmologists. But let’s assume that there are inaccuracies, errors and even stupidities in the monastery rules that prevent us from understanding and accepting the religion preached by the monastery? At least this needs to be said. And whether to listen to what was said or not is up to the monks and novices of the monastery (if the abbot allows it).