  The possibility of resorting to thisnesses might make us query whether the usual formulation of the Principle is correct. For as initially stated the Principle told us that no two substances exactly resemble each other. Yet if A and B otherwise exactly resemble each other then, on a common intuition, the fact that A has the property being identical to A while B has the distinct property being identical to B cannot result in a respect in which A and B fail to resemble each other.