How much is a brother worth? Targum Pseudo-Jonathan on (Genesis 37:28) gives the answer with almost unbearable precision. The Midianite traders pulled Joseph out of the pit and sold him to the Arabians for twenty mahin of silver. And then the Targum adds a detail the Hebrew only hints at: they bought sandals of them.
Twenty silver coins. Enough to buy a pair of shoes.
The prophet Amos, centuries later, would thunder against the rich of Samaria because they sold the poor for silver and the needy for a pair of sandals (Amos 2:6). The sages read Amos's line as a direct echo of the sale of Joseph. The brothers had begun a pattern in Jewish history: the moment when a human being becomes a price, and the price is small.
The liturgy remembers this. On Yom Kippur, the martyrology service recalls the Ten Martyrs — the sages executed by Rome — as a cosmic correction for the sale of Joseph. The ten brothers sold one. Ten sages gave their lives in return. The books do not balance easily.
And the sandals. Why sandals? Because sandals let you walk. The brothers, having sold Joseph, walked home in new shoes, leather warm on their feet, each step taken on the currency of their brother's life. The Targumist does not moralize. He simply names the shoes. And every reader for two thousand years has had to decide how to live in their own.