The human intellect is puny in comparison to the intellect of God. Peace comes into the liberated soul of a believer in Christ from the person of Christ. This peace has nothing to do with mans thinking or what man understands in any fashion. Only the supremacy of the person of Christ can liberate the soul of fallen man from the bondage of the Adamic Nature. Man can't figure out peace from God with his own mental process, nor can he find out how to achieve peace from God with his brain. God's peace passes "all" human understanding. Only God through the person of Christ can provide inner peace to the heart and soul of man.
Peace is also considered soul rest in the Bible. Soul rest is when the entire make-up and the entire character of fallen man is revolutionized and morally changed by the power of of Jesus Christ. Soul rest comes from God Almighty, not from human intellect or human reasoning. God provides perfect peace for the child of God. Peace with God from the outside, inner peace with yourself, and personal peace with the world around you. Peace comes upon the child of God when the Prince of Peace...Jesus Christ morally changes the heart of this believer. Human understanding is not involved with the peace of God.
Philippians 4:7... And the peace of God, which passeth all understanding, shall keep your hearts and minds through Christ Jesus