The study presented here focuses on the transformation in the 1940s and 1950s of Jan Patočka’s interpretation of the relationship between Socrates and Plato. This shift is tracked in the context of Patočka’s dialogue with the philosophy of existence. While in the lectures from the 1940s and the climactic work from this period, Věčnost a dějinnost (Eternity and Historicity), Socrates – with his emphasis on subjectivity, human freedom and incompleteness – is seen in Patočka’s conception to be close to the main motifs of the philosophy of existence, in Negativní platonismus (Negative Platonism) Patočka’s position is already far from such an “existential Socraticism.” The text of the study shows that Patočka’s critical reception of the philosophy of existence is one of the historically important motives in the transformation of Patočka’s position between Eternity and Historicity and Negative Platonism.