The "Milestones" provide a representative cross-section of Heidegger's thought from 1919 to 1961. They begin with a work on Karl Jaspers from the early stages of his own path, outlining philosophy as the original science of world-related life, in which the question of Being is formulated as the difference between "I am" and "something is - what." This is followed by texts from the period of fundamental ontological elaboration of the question of Being, addressing the relationship between phenomenological philosophy and theological science, the phenomenological destruction of Leibniz's ontology, the connection between Being and Nothing ("What is Metaphysics?"), and the transcendence as a threefold founding event of existence ("On the Essence of Ground"). This is followed by texts from the historical thinking of Being, starting with the transitional work "On the Essence of Truth.".