The midrash on Abraham's hospitality in Genesis 18 notices something small and opens it into a whole theology. The patriarch had just made a covenant with the peoples of the land. When three travelers appeared at his tent, he thought they were ordinary wayfarers — he did not yet know they were malakhim, angels — and he ran to prepare a feast.
He told Sarah to knead cakes (Genesis 18:6). But when the meal was served, the cakes never appeared. Why? Because Sarah became ritually impure mid-kneading, and Abraham, ever scrupulous, would not serve bread that had been rendered unfit.
So he ran to the herd and chose a tender calf (Genesis 18:7). And here the midrash adds its own detail. The calf, as if sensing its fate, broke loose and fled in terror. Abraham chased it, and the animal ran straight into the mouth of a cave.
It was the Me'arat HaMakhpelah, the Cave of the Double — and inside, Abraham saw something no one in his generation had seen. Adam and Eve lay there asleep on their couches, lamps burning steady above their heads, the air thick with a sweet fragrance that did not belong to this world.
In that moment Abraham understood where he was. This was the hinge of the world, the door the first humans had passed through on their way home. When the time came to bury Sarah (Genesis 23), he paid 400 shekels of silver for this very cave — not because he needed real estate, but because a runaway calf had shown him the doorway.