"But when the fullness of the time came, God sent forth His Son, born of a woman, born under the Law..." (Galatians 4:4)
In the Bible "the fullness of time" simply means when enough time had gone by. It is the point at which time itself has fulfilled its God-ordained course. God's timing is a crucial element in God's will being fulfilled. We must always be intent on God's timing as much as we are His will! This is what Paul is telling us in Galatians 4: 4. The time was right when Jesus, the Messiah was born. God Himself had preordained this important point in the History of time itself.
Jesus was born of a woman. The miracle of the His birth is that this woman was a virgin. (See Luke Chapter One) The essence of this miracle birth is the conception itself. Again, Luke Chapter One tells us that the Holy Spirit came upon young, teenage Mary and the power of the Most High overshadowed her. The child born was Holy because He was and is the Son of God! Remember...when the power of the Most High overshadows...stuff happens!
Jesus was born under the Law. He and His family observed every letter of the Law. "And when the days for their purification according to the law of Moses were completed, they brought Him up to Jerusalem to present Him to the Lord (as it is written in the Law of the Lord, 'Every firstborn male that opens the womb shall be called holy to the Lord'), and to offer a sacrifice according to what was said in the Law of the Lord, "A pair of turtledoves or two young pigeons." (Luke 2: 22-24) Jesus was born under the Law in order to fulfill the Law; by satisfying the requirement of the Law - righteousness.
How did Jesus fulfill the Law? By keeping the Law perfectly. He carried out every stroke of the Law perfectly and thus fulfilled it's requirement. Mankind, since the fall of Adam and Eve, simply was not capable of fulfilling the Law. But Jesus did because He was born of a woman, born of the Holy Spirit, and...born of under the Law! For 33 and a half years He fulfilled every requirement of the Law so that when He went to the cross He proved to be exactly who John the Baptist said He was, "The Lamb of God who takes away the sins of the world"! Man!! Is it any wonder we get excited when we delve into the essence of who Jesus is? He's much more than a cute little baby lying in a feeding trough. He is Messiah, the Christ, the Anointed One! He has freed us from the curse of the Law (judgment), and fulfilled the Law in us by making us the righteousness of God! Let Him into your heart NOW. He's knocking at the door of your heart.