Matthew 25:4

But the wise took oil. Under this parable, we have the state of all Christians in their mortal pilgrimage justly delineated. The wise took oil in their lamps, the necessary qualifications of grace and charity, joined with divine faith, and an additional supply of oil in their vessels; i.e. they laid up in store for themselves a solid foundation of good works. St. Gregory teaches, that by the lamps, faith is meant; and by the light, good works. Hence he concludes that the bad, although they have lamps, i.e. faith, no less than the good, shall be excluded; because their lamps are out, i.e. their faith is dead, without charity and good works to enlighten them. (hom. xii.) --- St. Augustine also declares, that these lighted lamps are good works, viz. works of mercy and good conversation, which shine forth before men. (ep. 120. chap. xxxiii.) --- And, that this oil is a right inward intention, directing all our works to the greater glory of God, and not to the praise of ourselves in the sight of men. (Idem. ibid. [St. Augustine, ep. 120. chap. xxxiii.]) --- The foolish virgins had a little oil in their lamps at first, sufficient to shine before men, by some little external shew of piety, or certain works done through fear, profit, or human respects; but had made no provision of solid piety and charity, by means of which they might, like the prudent virgins, produce good works to salvation. (Jansenius)