O Adonai, et Dux domus Israel,
qui Moysi in igne flammae rubi apparuisti,
et ei in Sina legem dedisti:
veni ad redimendum nos in brachio extento.
O Adonai, and leader of the House of Israel,
who appeared to Moses in the fire of the burning bush
and gave him the law on Sinai:
Come to redeem us with an outstretched arm.
Jesus came in the fullness of time. He will come again in the fullness of time. Wherever Jesus, the Christ, is the time is brought to its fullness.
We often experience our time as empty. We hope that tomorrow, next week, next month or next year the real things will happen. But sometimes we experience the fullness of time. That is when it seems that time stands still, that past, present, and future become one; that everything is present where we are; and that God, we, and all that is have come together in total unity. This is the experience of God's time. "When the completion of the time came [that is: in the fullness of time], God sent his Son, born of a woman" (Galatians 4:4), and in the fullness of time God will "bring everything together under Christ, as head, everything in the heavens and everything on earth" (Ephesians 1:10). It is in the fullness of time that we meet God.
Henri Nouwen, from Bread for the Journey
In the NRSV, these two passages expand as:
But when the fullness of time had come, God sent his Son, born of a woman, born under the law, in order to redeem those who were under the law, so that we might receive adoption as children. And because you are children, God has sent the Spirit of his Son into our hearts, crying, 'Abba! Father!' (Galatians 4.4-6)
With all wisdom and insight he has made known to us the mystery of his will, according to his good pleasure that he set forth in Christ, as a plan for the fullness of time, to gather up all things in him, things in heaven and things on earth. (Ephesians 1.8b-10)
I love this phrase, the "fullness of time" - pleroma tou chronos. Jesus is the Word, and where the Word is, all things are brought to wholeness, healing, completeness, fullness. All things come into being through him (John 1.3) and through him will all things be made whole (Revelation 21, Romans 8.18ff).
Christ is the mercy of God come among us, limitless and everlasting. "All shall be well, and all shall be well, and all manner of things shall be well." (Julian of Norwich)