"All 384 squares are equivalent." They can not be distinguished. In Galois theory -1 and 1, as well as i and -1, the quaternions i, j, k, -1, -j, -k can not be distinguished. When talking about different thinks we use conventions in order to have the same view on things looking from the same point of view. http://de.wikipedia.org/?curid=841867#Beispiele see http://commons.wikimedia.org/?curid=12208173 a real masterpiece