Final answer:
Utnapishtim and his wife prove Gilgamesh's week-long sleep with loaves of bread that mark each day's passing, exhibiting varying degrees of freshness.
Step-by-step explanation:
In the Epic of Gilgamesh, Utnapishtim and his wife prove that Gilgamesh has slept for a week by using loaves of bread as a measure of time. Each day, Utnapishtim's wife bakes a fresh loaf and places it next to Gilgamesh as he sleeps. When Gilgamesh awakens, he denies having slept for so long, but the presence of the multiple loaves of bread, each in varying states of freshness - from freshly baked to stale - provides tangible evidence that he indeed slept a whole week. This method cleverly uses the perishability of food to mark the passage of time, offering a simple yet effective way to counter Gilgamesh's disbelief.