"Do not think that I have come to abolish the law and the prophets. I have come, not to abolish them, but to fulfill them." (Mt. 5:17, NAB)
This is the first line of today's gospel reading.
Jesus wants us to think about him correctly. He wants us not to misunderstand His intentions, and mostly I think He doesn't want us meditating on ourselves, imagining God in our own image, but leaving the realm of our thoughts and entering into His.
And so He tells us not to think He's come to abolish the law and the prophets. Scripture is full of admonitions not to add to or subtract from God's word, specifically the directives He gives, and the prophetic messages He gives. He wants them just the way He gives them.
And yet... He gives them in such a way that they have an aspect of "emptiness" to them -- of lack of fulfillment. This is on purpose. The law, the prophetic messages, are given in such a way that they cause us to look deeper, to look beyond, to look for what they really hold. They are designed to cause even a certain dissatisfaction. It is when we want mastery over the mystery of God that we add our own embellishments or take away the more onerous or confusing bits from the law and prophets. But then we've made God over into our image, and made Him more manageable and palatable, suiting our current whim.
Christ is the fulfillment. What is more, Ephesians 1:23 tells us that the Christ is the head of the church, which is His body, the fullness of Him who fills everything in every way. Christ comes not only to personally keep the law and be the promised Messiah the prophets foretold. He comes to form the perfected people that the old covenant was never able to produce. This must be why He goes on (after the verse I quoted above) to talk about those who will be called greatest and least in the kingdom of God.
Still now, in the new covenant, we know in part and we prophesy in part. We too have that which causes a yearning in our souls. This also is by God's design, to draw us more deeply into the experience of His life, and to direct our gaze heavenward.