In The Phenomenology of Internal Time-Consciousness, Edmund Husserl distinguishes between the two temporal perspectives from which we experience: the present and the now. The present has duration; it is the temporal perspective from which we experience the temporally extended object of a single act of consciousness. A new act of consciousness takes place in a new present; each new act of consciousness effects the end of the previous present. This is easily demonstrated. Clap twice in quick succession, and focus on the sounds. The succession of clap sounds is a temporally extended object, which we hear in a single act of consciousness. The two claps make up one succession. The second clap is heard not as a separate and unrelated event, but as part of the succession, because it comes in the context of, or in relation to, the first clap. The entirety comes to us as a present perception, in a single act of consciousness. If this single act of consciousness has a duration of one second, it takes place in a present that has a duration of one second. The passage of railroad cars at a crossing is an example of a similar kind of temporally extended object. The sounding of an incomprehensible sentence is another. If I hear an incomprehensible sentence with a single act of consciousness that lasts ten seconds, then the present has a duration of ten seconds.