9 “But when that cry was made at midnight.” What cry was this, but that of which the Apostle says, “In the twinkling of an eye, at the last trump”? “For the trumpet shall sound, and the dead shall be raised incorruptible, and we shall be changed”? And so when the cry was made at midnight, “Behold, the Bridegroom comes;” what follows? “Then all those virgins arose.” What is, “they” all arose? “The hour will come,” said the Lord Himself, “when all that are in the graves shall hear His voice, and shall come forth.” Therefore at the last trumpet they all arose. “Now those wise virgins had brought oil with them in their vessels; but the foolish brought no oil with them.” What is the meaning of “brought no oil with them in their vessels”? What is “in their vessels”? In their hearts. Whence the Apostle says, “Our glorying is this, the testimony of our conscience.” There is the oil, the precious oil; this oil is of the gift of God. Men can put oil into their vessels, but they cannot create the olive. See, I have oil; but did you create the oil? It is of the gift of God. You have oil. Carry it with you. What is “carry it with you”? Have it within, there please God.
Source: Sermons on Selected Lessons of the New Testament (New Advent)