Leibn took the appearances for things in themselves, thus for intelligibilia,.e., objects of the pure understanding (although on account of the confusion of their representations he labeled them with the name ofphenomena),d and there his principle of non discernibility (principium identitatis in discernibilium), could surely not be disputed, but since they are objects of sensibility, and the understanding with regard to them is not of pure but of empirical use, multiplicity and numerical difference are al ready given by space itself as the condition of outer appearances.