What corresponds in empirical intuition to sensation is reality. A sensation occurs in an instant and is not extensive through time . The real, which corresponds to sensation in general, represents the concept which includes being. Of magnitudes in general, we can know a priori only a single quality, that of continuity. All else is left up to experience.
Experience is an empirical knowledge .
It is a synthesis of perceptions, not contained in perception but itself containing in one consciousness the synthetic unity of the manifold of perceptions. Since time itself cannot be perceived, the determination of the existence of objects in time can take place only through their relation in time in general. The three modes of time are duration, succession, and coexistence. The general principles of the three analogies rest on the necessary unity of apperception at every instant of time . These principles are not concerned with appearances, only with existence and relation in respect to existence.