From the Bremen lecture, Insight into That Which Is
The thingness of the pitcher consists in it being a container. We notice the containing of the container when we fill the pitcher. The bottom and sides of the pitcher evidently take over the task of containing. But easy there! When we fill the pitcher with wine, do we pour it into the sides and the bottom? At most, we pour it between the sides and onto the bottom. The sides and the bottom are the impenetrable aspects of the container. However, the impenetrable is not yet the containing. When we lift the pitcher, the liquid flows into the empty pitcher The emptiness is the containing of the container. The emptiness—this nothingness that belongs to the pitcher—is what the pitcher, as a containing container, is.
Yet the pitcher does consist of sides and a bottom. It stands by virtue of that of which it consists. What would a pitcher be that did not stand? At the very least, a failed pitcher; so still a pitcher—namely one that could contain—but one that would spill everything by constantly falling over.
A pitcher is a container, but not just a container with an inside and inside walls, but a container with a bottom. Gravity's always there in the background.