[Jesus asked His disciples,] "Do you understand all these things?" They answered, "Yes."
Finally, the disciples managed the correct answer.
Chapter 13 begins with the parable of the sower, which Jesus tells the crowd then explains to the disciples. Next is the parable of the weeds, which, once behind closed doors, the disciples ask to be explained. After His explanation, Jesus tells them the parables of the buried treasure, the pearl of great price, and the net thrown into the sea.
So, after having to have explained two longer parables to them, the disciples are told three short ones and asked if they understand them.
Jesus takes them at their word (an uncomfortable thought, perhaps, for Christians who pray liturgically; "Didn't you say you wanted My Father's will done on earth as it is in heaven?") instead of pressing the point. I wonder, though, how deep their understanding -- an echo of Solomon's request for "an understanding heart" -- at that time went. A pearl of great price? Understandable. A pearl beyond price, bought at a price beyond price? Not so much.
We can think in terms of a treasure worth a bajillion dollars, obtained at the cost of a thousand dollars. But if we truly understand the kingdom of heaven, we understand that it is not worth a bajillion dollars; it's worth more than everything.
Being a disciple of Christ isn't simply worth more than what must be given up. If that were the case, the economics could in principle shift around and something else wind up worth more than the kingdom of heaven. Pearls have no intrinsic value; if the market collapses after the merchant buys the pearl of great price, he's out of luck. And if someone just doesn't care for pearls, he won't be convinced to buy it, no matter what it's worth.
This is what we need to understand about the kingdom of heaven. It isn't simply the greatest good according to some accidental ordering of goods; it isn't the good you get to by moving from lesser good to greater good until you reach a global maximum; it's not the limit of all created goods. The kingdom of heaven is the sharing in the Divine Life of the Trinity, and that is a good beyond all goods, a good so good calling it "good" is almost a lie.
Do we understand this? "Yes," we say. But how do we live?