Joseph’s final plan to “incriminate” his brothers is to send them back to Canaan again. But before they leave he slips his silver cup into Benjamin’s grain sack. This is Pharaoh’s cup, and the one with which he practices divination. Water divination was a common practice in Egypt, a method of determining the future. One might read the pattern of drops that fell from a cup, or one might throw something into the water in the cup, which would form patterns that were omens.

The brothers maintai…