<human>:  In Heidegger’s Being and Time, where does he say that the world is a phantasm?
<bot>: Heidegger says that the world is a phantasm in Being and Time, Book 1, Chapter 1. In this chapter, Heidegger discusses the concept of Dasein, which is the being that is present-at-hand. Dasein is the being that is aware of its own existence. Heidegger says that the world is a phantasm because it is not real. The world is a collection of things that we perceive, but the world is not real.