As to organic bodies, so far as they _are_ bodies, or corporeal, they are one and identical only in appearance. "They are not the same an instant. . . . Bodies are in constant flux." "They are like a river which is always changing its water, or like the ship of Theseus which the Athenians are constantly repairing." Such unity as they really possess is like all unity,--ideal or spiritual. "They remain the same individual by virtue of that same soul or spirit which constitutes the 'Ego' in those individuals who think." "Except for the soul, there is neither the same life nor any vital union." As to personal identity, Leibniz distinguishes between "physical or real" identity and "moral." In neither case, however, is it a unity which excludes plurality, an identity which does not comprehend diversity. "Every spirit has," he says, "traces of all the impressions which it has ever experienced, and even presentiments of all that ever will happen. But these feelings are generally too minute to be distinguished and brought into consciousness, though they may be sometime developed. This _continuity_ and _connection_ of _perceptions_ makes up the real identity of the individual, while _apperceptions_ (that which is consciously apprehended of past experiences) constitute the moral identity and make manifest the real identity." We have had occasion before to allude to the part played in the Leibnizian philosophy by "minute perceptions" or "unconscious ideas." Of them he says, relative to the present point, that "insensible perceptions mark and even constitute the sameness of the individual, which is characterized by the residua preserved from its preceding states, as they form its connection with its present state." If these connections are "apperceived" or brought into distinct consciousness, there is moral identity as well. As he expresses it in one place: "The self (_soi_) is real and physical identity; the appearance of self, accompanied with truth, is personal identity." But the essential point in either case is that the identity is not that of a substance underlying modifications, nor of a consciousness which merely accompanies all mental states, but is the connection, the active continuity, or--in Kant's word--the synthesis, of all particular forms of the mental life. The self is not the most abstract unity of experience, it is the most organic. What Leibniz says of his monads generally is especially true of the higher monads,--human souls. "They vary, up to infinity itself, with the greatest abundance, order, and beauty imaginable." Not a mathematical point, but life, is the type of Leibniz's conception of identity.