Do not labor for the food which perishes. The first work is to believe in Him whom He sent, yet God is also concerned about our obedience.
In this sense our faith in Him is not a substitute for works; our faith is the foundation for works that truly please God.
A parent does not only want obedience from their child; a relationship of trust and love is even more important to the parent.
Obedience grows out of that relationship of trust and love. God wants the same pattern in our relationship with Him.
Jesus tried to lift their minds above earthly things and on to heavenly realities; to an understanding that He is necessary for spiritual life just as bread is necessary for physical survival.
When we are hungry, we feel as though food will answer all our problems. It’s the same way with almost all other practical difficulties we find ourselves in. Just as Jesus tried to lift their understanding above their material, physical needs, so we need to have our minds lifted.