This 1940 essay was published in 1942 and is based upon the Winter Semester 1930–31 lecture course on the essence of truth. It is an interpretation of Plato’s famous metaphor of the cave in which Heidegger shows how Plato transformed the early Greek understanding of being as φύσις, and of ἀλήθεια as unconcealment, into a doctrine of ideas and truth as correctness. The beingness of an entity is an idea, εἶδος, that is, the way in which it shows itself and comes to presence. The privileged relation between apprehending, νοεῖν, and idea in Plato’s philosophy is at the origin of the explication of λόγος as reason. Since the beingness of an entity is its idea as constant presence, ἀλήθεια becomes the correctness of the correspondence between knowledge and its object. The correctness is expressed in assertions and thus judgment becomes the primary place of truth.