This text critically engages with the concepts of experience and the world as presented by Martin Buber in his work "I and Thou." The author challenges Buber's assertion that the one who experiences does not participate in the world and that the world remains unaffected by experience. Instead, the author argues that without reactivity and the mutual interaction of beings, a real world would not exist, remaining merely virtual. This perspective differs from Berkeley’s subjective idealism; here, perception and experience are understood as real reactions to reality, which are themselves inherently real. Through the processes of experiencing and reacting, the world is both preserved and transformed. A fundamental premise of existence is the capacity to elicit a reaction; an entity to which nothing reacts is effectively non-existent. The text emphasizes the ontological significance of reactibility as a key element in the constitution of the real world, rejecting the strict separation between the experiencing subject and the experienced object.