We have all heard about the "peace of God, which passeth all understanding", and we are used to hearing "peace be with thee/And with thy spirit" in the Eucharist. But what is this peace the Bible talks about? There is an exhaustive lexical and contextual analysis here: http://biblehub.com/greek/1515.htm, which I won't attempt to reproduce. But it's a huge word, with a range of meaning as wide, but also as coherent, as a rainbow.
First, there is, well, peace. Not war. Those of us old enough to have been born before or during World War II have a visceral feeling about, and for, peace in that sense. In his novel The Empty Room (1942), Charles Morgan shows some people in England talking about the distant past and a hoped-for future. One evening, says one of them, some friends will sit together, talking in a garden, and one of them will say, with wonder and contentment, "A June night, and no war." Perhaps there are people in Syria today who feel the same way. It is eirènè, the fundamental meaning of that lovely Greek word, and the reason that the Dutch princess born during WW II was named Irene. Peace as a public condition, a condition of not-war, is never to be taken for granted. It is huge, a privilege, and should be savoured daily by those fortunate enough to live in it.
Then, there is peace as a condition between people. Here, the meaning is closer to harmony: an absence of strife, of quarrel, of awkwardness, of hostility. It is an emotion elevated to a condition, which means that it is felt by the heart rather than, or prior to, being understood by the mind. It is the peace sometimes seen in very old long-married couples whose love has over the decades been distilled to a fine and almost silent essence. It is the peace between true friends engaged together in some activity long known, long practiced and long loved. And notice that both these examples remind us that peace between individuals often has time as a component element.
There is the peace of science, or of scholarship. This is a peace experienced individually. It is the peace found by someone working tranquilly at some project within one's competence and which, again, requires time to mature and complete. It is a peace I have experienced while working in great research libraries: Duke Humphrey's 15th-century library in Oxford's Bodleian, the 17th-century Manuscript Room of Paris's Bibliothèque nationale. It is a peace composed in part of a going out of one's self, of losing oneself in a subject, in the life of another age, in the patient search for a clue. A similar peace is found, we are told, by writers, novelists for the most part, when they are engaged upon a lengthy task in propitious surroundings. The great Dutch poet Adriaan Roland Holst experienced it during the six long winters, in the1930s, when, in his little thatched cottage behind the North Sea dunes, he worked concentratedly on his masterpiece, the long, dense poem known as A Winter By The Sea.
Such peace touches, and sometimes becomes, a peace of the spirit. This peace is known by some philosophers, by some contemplatives, by those who in one way or another have reached a true wisdom. In some societies such men and women are revered as sages; in others, they live unknown in corners of the world, sometimes with a small group of pupils, sometimes alone, quietly engaged in some trade and encountered by chance. I have known a watchmaker like that; a former paratrooper; a retired journalist who studied mysticism; and a professor of Indian philosophy. In some, this peace of wisdom can be and is expressed in words; in others, it communicates itself intangibly, mysteriously but unmistakeably.
All peace that is not cowardice is good. But it does not really, not truly, not completely pass oour understanding. It is not the peace of God. What, then, is?
Reading the Bible, Old Testament and New, one sees little peace. Humanity seems always at war with itself; Israel with its neighbours; Israel with its God; heroes with other heroes or with bloodthirsty monsters; brothers with brothers, fathers with sons; and the Serpent with everyone. Where, then, is the Peace of that God the Scriptures describe, explain, and adore? We find it, sometimes, in the Psalms. The Psalmist, nominally King David, finds peace in the Law, which shows him a way through a trackless desert. He finds peace in adoring God, in being, as he says, an olive tree in the house of the Lord. And above all, remember that the term we are seeking occurs in a blessing; may the peace of God, which passeth all understanding, keep our hearts and minds in Christ Jesus (Philippians 4:7). One translation has guard for keep, which helps us understand. The peace of God, then, is something that keeps us, that guards us, that protects us from harm. It does so in Christ Jesus: which is a whole story unto itself. We are in Christ when we are a part of him; for since the Resurrection he is present wherever those who love God, the Father, the Son, and the Holy Spirit, are present -- as a congregation especially, in the Eucharist especially, but in prayer, in meditation, in contemplation also. And since he is Love, in the Spirit he not only neighbours us with his presence, but he surrounds us, he enfolds us; and when this happens, each time it happens (because in this mortal life it is never once and for all, not yet), we have come home. That is the peace of God: our homecoming to the relation he always intended, to the hearth of the Father's house.