the-REAL-me-inside

There's something that always bothered me, maybe someone can explain it for me: ***Before I get started, a DISCLAIMER: I am NOT trying to be rude, insensitive, or in any other way disrespectful to any particular group or handicap, its just my personal questions and curiosity.*** That being said, I don't understand Braille signs. How are the blind supposed to find a sign six inches in diameter on a six by twelve wall??? Do they just run their hand up and down the wall till they find it? How to they know how high it is from the floor and how far it is from the door? And when they finally do find it, how can said person be sure that it labels