Burke discusses the origins of the feast and how it has no mention in the Bible. However, he briefly explains quite well the how and the why behind Catholic tradition.
This doctrine is not found in any definitive way in the scriptures, which is not a significant factor to Roman Catholics who believe that divine revelation is both in scripture and sacred oral tradition. The Bible did not come before the church but the Church came before the Bible. Indeed, it was the church that put the Bible together by putting all of its sacred books into one volume. The Bible itself points to sacred oral tradition.
At the end of the gospel of John, the writer says that if everything that Jes us did was to have been recorded, all the books in the world could not contain it. And St Paul in his second letter to the Thessalonians Chapter 2 verse 15 states, "Stand firm brethren and safeguard all traditions whether written or by word of mouth."
Just before giving the above explanation, Burke gives this example of Divine approval of the doctrine behind the feast:
The reported apparitions of Bernadette Soubirous of Lourdes in France in 1858 and the subsequent miraculous healings seem to suggest that Almighty God concurs with the doctrine. Bernadette, an illiterate shepherd girl, reported visions of a lady who identified herself as the Immaculate Conception. The lady told her about a stream that would flow and heal people. As many as 705 doctors, many of whom were not Roman Catholic, appointed to investigate the claims, reported that the healings were beyond medical comprehension.
After summarizing the Second Vatican Council, Burke concludes with why Catholics hold up the Virgin Mary and pay so much attention to her.
No wonder then, that the council ended on the feast of the Immaculate Conception. The church holds up the Blessed Virgin Mary as the principal role model for all of mankind to follow. Mary the queen of peace and the first Christian, is a symbol of the unity that her son Jesus Christ taught and instituted in the Eucharist at the feast of the Passover on the night before he was crucified. The Blessed Virgin Mary is testimony that we can live a life in following the teachings of Jesus Christ. And Mary's greatness was in saying yes to the Lord.
The entire column deserves reading in its entirety. Go check it out.