NOTES for Mat 4:4
What does it mean that "man shall live"? Does bread, does food, not sustain life in us? Biological life, yes. But plants also feed and live. Is that vegetating even in the slightest degree like human life, is it worthy of a human being? Thanks to school education, by the word life we mean "metabolism" and nothing more. Life for us, as one rather unattractive thinker of the 19th century said, is "the mode of existence of protein bodies." Students at the end of the 20th century added: "the best mode..." No, life is not that. Life is something directly connected with meaning, beauty and immortality, love and openness, joy and truth... And life can also be given to others without losing it.
The words from Deuteronomy quoted by the Lord Jesus say that a human being can receive an entirely different life, eternal life, like the life God Himself possesses. For the breath of life that the Spirit of God places in a person cannot be limited by time. The source of this life is only God Himself, and He shares it with a person through "every word that proceeds from the mouth of God." And the word God speaks to a person becomes food, that which sustains eternal life in us. But one must suppose that these words contain another important aspect as well; to see it, it is enough to set aside the word "every." God gives us His life not only, and not so much, by the word He speaks to our heart. Above all, the eternal life of a human being is sustained by the Body and Blood of the Lord Jesus Christ, the Word of God who has come to us.