In (1) apperception is almost equivalent to self-consciousness; the existence of the ego may be more or less prominent, but it is always involved.
In Kantian terminology apperception is (1) transcendental - the perception of an object as involving the consciousness of the pure self as subject, and (2) empirical, - the cognition of the self in its concrete existence.
Further, on his own account, he identifies apperception with the process of attention, and regards it as an act necessary to the general formation of compound ideas, to all association of ideas, to all imagination and understanding.
Such mentally endowed substances might be called souls; but, as he distinguished between perception and apperception or consciousness, and considered that perceptions are often unconscious, he preferred to divide monads into unconscious entelechies of inorganic bodies, sentient souls of animals, and rational souls, or spirits, of men; while he further concluded that all these are derivative monads created by God, the monad of monads.
Immediate spontaneous apperception may seize this supreme reality; but to vindicate it by reflection as an inference on the principle of causality is impossible.
It is the analysis of an aggregate idea (Gesammtvorstellung) into subject and predicate; based on a previous association of ideas, on relating and comparing, and on the apperceptive synthesis of an aggregate idea in consequence; but itself consisting in an apperceptive analysis of that aggregate idea; and requiring will in the form of apperception or attention (Wundt).
The truth is that Cousin's doctrine of the spontaneous apperception of impersonal truth amounts to little more than a presentment in philosophical language of the ordinary convictions and beliefs of mankind.
It is this unity of apperception which enables us to combine the data of more than one sense, to affirm reality, unreality, identity, difference, unity, plurality and so forth, as also the good, the beautiful and their contraries.
Wundt, in consequence, thinking with Kant that apperception is a spontaneous activity, and with Fichte that this activity requires will, and indeed that all activity is will, infers that apperception is inner will.
In accordance with his previous division of outer will into impulsive and decisive, he divides the inner will of apperception into passive apperception and active apperception.