In the sixth commandment marriage with non-Catholics is for bidden, also the marriage of those who are related within the fourth degree of kindred. Marriages are not to be solemnized during fixed seasons. These penitential times are from the beginning of Advent until the Epiphany, and from Ash Wednesday until Low Sunday.
This rule was made by the Council of Trent (Council of Trent, 24, 10). Formerly the prohibition also included the period between the Monday of Rogation week until the first Sunday after Pentecost; in some countries at the present time it applies to the Rogation days and all fasts throughout the year. Advent and Lent are seasons of penance and sorrow for sin, and festivities ill accord with sorrow. Moreover in Advent the Church proposes the mystery of the Incarnation, and in Lent the mystery of the redemption for our meditation, and it would be unseemly to divert our minds from these solemn subjects by worldly amusements. The bishop can give per mission for marriages to be contracted privately during these times; for their public solemnization the authorization of the Holy See is necessary. Concerts are not forbidden, but dances are. Those who transgress this command expose themselves to the judgment God threatens by the prophet: “I will turn your feasts into mourning” (Amos viii. 10).