The Catechism in Questions & Answers

157. What did Jesus reveal in the parables of the coming of the Son of Man?

In the parables of the coming of the Son of Man, Jesus Christ spoke of His return.
In Matthew 24: 37-39 a comparison is made between the time before Jesus’ return and the days of Noah. What is clear from this is that the return of Christ will be sudden and surprising.
This message is also imparted by the parable of the wise and foolish virgins (cf. Matthew 25: 1-13). From this we learn to watch and be prepared for the return of the Lord.

“But as the days of Noah were, so also will the coming of the Son of Man be. For as in the days before the flood, they were eating and drinking, marrying and giving in to marriage, until the day that Noah entered the ark, and did not know until the flood came and took them all away, so also will the coming of the Son of Man be.” Matthew 24: 37-39
“Then the kingdom of heaven shall be likened to ten virgins who took their lamps and went out to meet the bridegroom. Now five of them were wise, and five were foolish. Those who were foolish took their lamps and took no oil with them, but the wise took oil in their vessels with their lamps. But while the bridegroom was delayed, they all slumbered and slept. And at midnight a cry was heard: ‘Behold, the bridegroom is coming; go out to meet him!’ Then all those virgins arose and trimmed their lamps. And the foolish said to the wise, ‘Give us some of your oil, for our lamps are going out.’ But the wise answered, saying, ‘No, lest there should not be enough for us and you; but go rather to those who sell, and buy for yourselves.’ And while they went to buy, the bridegroom came, and those who were ready went in with him to the wedding; and the door was shut. Afterward the other virgins came also, saying, ‘Lord, Lord, open to us!’ But he answered and said, ‘Assuredly, I say to you, I do not know you.’ Watch therefore, for you now neither the day nor the hour in which the Son of Man is coming.” Matthew 25: 1-13