Mat 4:4 It is written, Man shall not live by bread alone, but by every word that proceeds out of the mouth of God.
Alternative: It is written. Humanity will not be filled with life by food alone but by every matter that is produced out of the speech of the divine.
In Greek, the word we translate as "tempt" is peirazo, which also means "to try if something can be done" or, more simply, "a trial" or "testing." In this context, Satan can be seen as someone who tests us. Temptation is not evil in itself, but it is designed to test our metal. (This view of Satan as a tester for God rather than as the opponent of God is consistent with the first biblical mention of Satan in the story of Job.) This story of testing are interesting in that, though not entirely written in Christ's words, they could have only come from Christ telling his disciples about them. There weren't any other witnesses except for Christ and his tester.
First, notice that here, Jesus does not speak from his own authority. When he says, "it is written," he is quoting Deu 8:3. In it, Moses describes the hunger and suffering of the Jews in the desert and how God sent them mana. The following verse of Deu 8:5 may also be considered a provocative prophesy of Christ's suffering and death.
In the next part of this statement ("man does not live by bread alone..."), Jesus identifies the first type of tests that we must face in life, the needs and desires of our a physical body. Our desire for physical gratification is our first and most powerful motivation to do wrong. We can justify all manner of evil by claimed we need to do it for our physical survival. This is a central theme of Jesus's life lesson: by trying to save our temporary physical life we will lose our eternal, spiritual life, but by sacrificing our physical life we will win eternal life.
However, notice that he doesn't make the spiritual superior to the physical. He equates them. Life comes from both the physical and spiritual. This is clear from the word used here for "live." The Greek term, zao, means not only to life and breath, but to enjoy life as well.
Jesus finishes this verse with the most curious part of this quote. "...but by every word that comes from the mouth of God."
Though most of this site is dedicated to the Greek, when Christ quotes from the OT, we have the opportunity to look at the NT Greek with the OT Hebrew, in this case, of Deuteronomy, which is what Christ points us to with this quote. The Hebrew is mowtsa peh Yehova, "that rises from the mouth of the existing one." Three interesting observations about this statement.
First, mowtsa means simultaneously the source of something going forth, the thing that goes forth, and the way of going forth. It doesn't really mean words, as such. It is God, the gift of God, and the path by which God makes contact with us. It is the divine outpouring, which joins the divine with creation. In the Greek, the word used for "word" is not logos, which is the word that Christ most often uses to describe his own words. It is the basis of our word "logic" and all the English words describing types of knowledge that end in "ology." Instead, the word used is rhêma, that has the sense of the outpouring of language rather than the meaning of words.
Next, is the word, peh, which most commonly means the organ people and animals use for talking and eating but also means an extremity or end. The mouth is one end of the alementary canal. God doesn't have an physical mouth, as such, but He as an organ for communication, an extremity that touches humanity. The Greek word, stoma, is much more an organ of speech or simply any inlet or outlet.
Finally, we have Yehova, the unpronounceable name of God, translated most commonly in the Bible as "Lord" but occasionally as "God." It means literally "the existing one," from the root hayaw, "to be, become, or exist." This is the name that sets God apart from everything else. It originally come from the burning bush as "hayaw hayaw," which we translate as "I am that am," but which also means something like "being to be" expressed originally as a verb. (In the his original words about himself, God is a verb, not a noun.) As a noun this phrase might be, "the being (or becoming) of existence" or more simply, Yehova, th existing one.
So what is Christ saying about how we meet the challenges of our physical needs? To trust our ancient wisdom not the cravings of our body and that our life really comes from the outpouring that touches us of the foundation of existence.
However, like most of Christ's statements, this statement raises even more questions about the nature of human life and the nature of existence. What is that outpouring from existence, those words of God? Christ himself is described as the Word made flesh. The Holy Spirit is described as God's outpouring. There are deeper mysteries here that Christ answers later in his teaching.
As a hint of things to come, think about Christs use of the term "bread." What is the bread of life? Bread is the center of a stream of metaphors that connects seeds, to the growth of plants, to the harvest of grain, to the kneeding of yeast into bread, to the bread itself, to bread becoming flesh, to flesh becoming spirit. Remember, hayaw means to exist, but it also means "to become." One thing that sets Christ's words apart from the way we talk is that he always see the becoming of things, not just their existence. God is a verb, not a noun.
"It is written" is from graphô (grapho), which means "to write," "having marked or drawn," "to describe," "to brand," "to express by written characters," "to ordain," "to enroll oneself," "to be indicted," and "to write down."
"Men" is from anthrôpos (anthropos), which "man," and, in plural, "mankind." It also means "humanity" and that which is human and opposed to that which is animal or inanimate.
"Live" is from zaô (zao), which means "to live," "the living," and "to be alive." It is a metaphor for "to be full of life," "to be strong," and "to be fresh."
"By" is from epi, (epi) which means "on," "upon," "at," "by," "before," "across," and "against."
"Loaves" is from artos (artos), which means specifically a "cake of whole wheat bread," and generally "loaf," and "bread."
"Only" is from monôs (monon), which means "alone," "solitary," "only," "one above all others," "made in one piece," "single," and "unique."
"Word" is from rhêma (rhema), which means "that which is spoken," "word," "saying," "word for word," "subject of speech," and "matter."
"Proceed" is from ekporeuô (ekporeuomai), which means "to make to go out," "to fetch out," and "to march out."
"Mouth" is stoma (stoma), which means "mouth," especially, "the mouth as an organ of speech," "speech," "utterance," "any outlet or entrance," and "the foremost part" of something. For example, the blade of a weapon is a stoma.