Philosophy is often seen as a tradition. Each significant philosopher studied his significant predecessors, found them faulty in various respects, and embarked to correct them. Aristotle corrected Plato, Descartes corrected the scholastics, and Heidegger corrected the whole history of thought since the pre-Socratics.
Philosophy appears as a long backward movement into the future, driven by close reading of predecessors. Such an image is understandable in a time when philosophy is being eaten up by the study of it. We are like archaeologists of thought, trying to reconstruct philosophy through the traces it left behind in our bookshelves. We thus imagine that philosophers were above all readers of philosophical texts: super-scholars with amazing skills of close reading, enabling them to identify the weak points of their predecessors’ work.
The paradox of this view of philosophy is that the textual residues we study don’t look like scholarly texts. Perhaps because philosophers weren’t moving backwards into the future, meticulously studying earlier texts, but were above all sensitive to the times in which they lived and tried to face the future well. That is how they “read” their predecessors.