Listen now | From the audiobook Explanation of Catholic Morals - Chapter 52, "Worship of Rest: Participation in Public Worship," outlines the Church's distinction between permissible and forbidden works on the Lord's Day. Liberal works, primarily intellectual (like reading or studying), are generally allowed as they don't impede divine worship, regardless of payment or fatigue. Conversely, servile works, which primarily involve bodily effort and manual labor, are forbidden because they detract from the focus on God and prevent necessary bodily rest. While there are exceptions for necessity, God's greater glory, or the good of one's neighbor, the general obligation to abstain from servile work remains absolute, making its transgression a sin, the gravity of which depends on the offense's nature.