By virtue of its own inner light the human intellect knows about its present life and about many things which at one time were present. Its knowledge of what lies in the past, however, is fragmentary, and what lies in the future can only be anticipated with some degree of probability in some particular details. In its larger expanse, the future remains indefinite and uncertain--though conceivable in this indefiniteness and uncertainty--while the origin and ultimately end remain completely inaccessible. And the immediately certain life of the present is merely the fleeting fulfillment of a passing moment, instantaneously sinking away and completely disappearing forthwith. My entire conscious life is not equivalent to "my being." Rather, it resembles the lit surface that covers an obscure depth, a depth which manifests itself in and through the medium of the surface. If, then, we want to understanding the human being-person, we must penetrate this obscure depth.
Edith Stein, Finite and Eternal Being, Reinhardt, tr. ICS Publications (Washington, DC: 2002) p. 364.