Catechism of the Catholic Church

The fourth precept ("You shall observe the days of fasting and abstinence established by the Church") ensures the times of ascesis and penance which prepare us for the liturgical feasts and help us acquire mastery over our instincts and freedom of heart. (2177, 1387, 1438, 1351) The fifth precept ("You shall help to provide for the needs of the Church") means that the faithful are obliged to assist with the material needs of the Church, each according to his own ability. The faithful also have the duty of providing for the material needs of the Church, each according to his abilities.