Today's Gospel is from Matthew's "Parables of the Kingdom" section (chapter 13): the hidden treasure and the pearl of great price. We probably all tend to look at these images as parallel, whereas there is a good possibilty that they are mirror images of each other, and that, as Robert Frost would say, "makes all the difference."
In the first image, Jesus says "the Kingdom of Heaven is like a treasure hidden in a field." The lucky person who stumbles upon it immediately calculates its value, and thinks nothing of selling everything in order to buy the whole field. While people have been scandalized by this parable (technically, the buyer had a moral obligation to inform the owner of the true worth of the property), the ethics of buying and selling are not the point. The whole point is that the "treasure" of the Kingdom outweighs all our other possessions. It is worth divesting ourselves of everything to possess.
The second image seems to say the same thing, but there is a rather significant difference. Here, the "Kingdom of Heaven is like a merchant." The focus has shifted: in the first parable, the Kingdom was "discovered". In the second, the Kindom is the seeker. In both, the "Kingdom of Heaven" is GOD. So God is the merchant, and God "discovers" us as his pearl of great price, and God "sells all" to make us entirely his.
There is a hint of this parable in St. Paul's exhortation to the Corinthians: "You have been purchased for a price! So glorify God in your body" (1 Cor. 6:20). (The Greek words for "purchased" and "price" are the same in Paul and in Matthew, though Matthew's version has the prefix "poly" to indicate "great price.") Paul also, of course, gives us the marvelous hymn in Philippians 2 in which Jesus "despoiled himself", and in the next chapter, Paul describes how he himself had "sold everything" for the sake of Jesus. It could almost be the "autobiography" of the man who found the treasure in the field: "the things I once considered gain, I now reappraise as lost for the sake of Christ."