A blade of grass is a commonplace on Earth; it would be a miracle on Mars. Our descendants on Mars will know the value of a patch of green. And if a blade of grass is priceless, what is the value of a human being?
A miracle is an event which creates faith. That is the purpose and nature of miracles. Frauds deceive. An event which creates faith does not deceive: therefore it is not a fraud, but a miracle.
There are three forces, the only three forces capable of conquering and enslaving forever the conscience of these weak rebels in the interests of their own happiness. They are: the miracle, the mystery and authority.
In the Catholic Church, there are many other things which most justly keep me in her bosom. The consent of peoples and nations keeps me in the Church; so does her authority, inaugurated by miracles, nourished by hope, enlarged by love, established by age. The succession of priests keeps me, beginning from the very seat of the Apostle Peter, to whom the Lord, after His resurrection, gave it in charge to feed His sheep (Jn 21:15-19), down to the present episcopate.