According to Luke, Jesus spent forty days in the wilderness, where he was tempted by Satan. One of Satan's challenges was, “If you are the Son of God, command this stone to become bread.” Jesus answered, “It is written, ‘Man shall not live by bread alone,’” referring to the words in the Old Testament Book of Deuteronomy: “Man doth not live by bread only, but by every word that proceedeth out of the mouth of the Lord.”
The expression is frequently used to point out that worldly goods are not enough for most people; they need spiritual fulfillment as well.
