Now if one asks whether dualism alone holds in the doctrine of the soul, then the answer is: Of course, but only in the empirical sense,.e., in the connection of experience matter as substance in appearance is really given to outer sense, just as the thinking I is given to inner sense, likewise as substance in appearance; and in the connection of our outer as well as our inner perceptions, appearances on both sides must be connected among themselves into one experience according to the rules that the category of substance brings in.