Modern man doesn't much like Mysteries. They remind us too much of our limitations & finitude. We don't mind them in stories when they eventually resolve themselves - usually by our own wit - into a self-gratifying conclusion. But Mysteries before which we simply stand dumbfounded & "fold the wings of the intellect"? Not so much.
Christians holds for many Mysteries, but the central Mystery, the one on which all others dependant & without which all vanish like a vapor is the Holy Trinity - one God in Three Persons. It cannot be reasoned; man cannot figure this out on his own; it can only be revealed by that same Trinity.
St. Thomas said that truth is reality in accord with right reason. When we perceive something to be a certain way & it really is that way, then we have stumbled upon the truth. The truth resonates with human beings. Despite our fallen condition, we still intuitively seek the truth. In fact we crave it. For one, the success of Law & Order testifies to this.
When it comes to God; however, the truth is so overwhelming that many balk at attaining to it. It goes without saying that our own limitations posit no obstacle for God in revealing himself & continually calling us. However, he does require our cooperation & consent. Yet, so many balk...
In many ways, our responses to this invitation to know & participate in this Mysterious Truth are like Jesus' parable of the sower of seed (Matthew 13). We come up with all kind of schemes to avoid staring straight into the heart of this Mystery. Three things come to mind. We profess belief with our mouths but not with our hearts & lives. We alter the Truth to something more palatable - perhaps the most common today. Or we simply turn our backs, throw up our hands, declare that the truth is unknowable, & get on with the practicalities of life.
The point Father made in his homily is that, while we cannot know everything about a Mystery, it does not follow that we cannot know anything about it (BTW, this is where the Church runs afoul of so many today - it actally has the gall to claim that it is the custodian of the fullness of revealed truth, & that any other person or institution is, by definition, deficient). It means that no matter how much you yearn, no matter how much you explore, & no matter how much you strive to learn, there is always more & richer depths to plumb. In mathematics, it would akin to the properties of ininite numbers. It is reasonable that this "ever knowing more" is part of the experience of the Beatific Vision.
Note that my usage of Mystery & Truth has somewhat merged, which might seem a paradox. Yet, they truly are one, because they are ultimately God himself. A God that loves us & calls us to communion with him. Yet, the father of lies plants that evil seed & we doubt whether there is really an attainable truth. Maybe it is all man's attempt to explain the world we observe before the advent of modern science. Maybe there is no God. Or maybe we simply have no way to know.
And here our human nature, without any reference to revelation, comes to our aid. If there is no God, then we are just a random occurence, merely the most articulate of all animals. Then we are freed of any moral obligations & perfectly justified in tearing at each other as competitors for vital resources, even if the competitor is mother's own child in the womb. What a dismal picture of humanity emmerges, but one that doesn't really jive with our natural sense of worth & dignity; the produndity of the depth of our own being & of others around us; our desire to love & be loved. It is clear that man is an uncomfortable sojourner on the earth, always searching, always questioning, never content.
It is in this longing that we turn our minds upward - a metaphor for reaching above the carnal earth. We recognize a likeness of ourselves to the Other. We hear when he calls us. Our souls find solace in his presence. We find our higher purpose. We find in the heart of this Mystery Truth.
I could go in a hundred different direction here, relaying all kinds of sincere conversations or bizarre encounters I've had about how we can possibly know the truth of anything. I encourage you not to let anyone shake your faith on this. You can approach this Truth, you can enter into this Mystery simply because God wants you to.
Photo of Immaculate Conception Cathedral in Hangzhou, China taken in May 2010.