The birth of Jesus is described as happening "in the fullness of time." Over against our usual understanding of the flow of time (days, months, years, etc.), the word used here for "the fullness of time" means the God-appointed time, the supreme moment, when something special happens. This is the coming of God's Son, Jesus, whose birth "in the fullness of time" would lead to his suffering, death, and resurrection - all for us and for our salvation.