Thinking, Heidegger never fails to remind us, is preliminary. But the reason for this, its preliminary nature, is often, and quite wrongly, understood as the limitation of a perspectival horizon ---as if this preliminary nature of thinking were simply the result of the fact that "one can always learn more." But the preliminary nature of thinking consists in just the opposite: one already knows too much --indeed long before he has ever tried to think about what it is that he already knows. The preliminary nature of thinking has nothing to do with the constantly expanding itinerary of some "philosopher of infinite tasks". It is rather a consequence of the radical confinement of thinking to what it already has to think; the proper matter always comes too late to thinking, refusing thinking the luxury of "forging ahead", compelling it to retract itself from the outset, taking back its very beginning. Therefore, it must be vigilantly recalled that the preliminary nature of thinking is a consequence of its dilatory arrival. The thoughtful word hesitates. Otherwise, what there is for thinking to first of all think would be missed entirely.
It is with this dilatory essence of thinking in mind that Heidegger writes in his letter to Jean Beaufret:
Things that really matter, although they are not defined for all eternity, even when they come very late still come at the right time.