Vatican II on Celebrating Saints in the Liturgical Year

Sacrosanctum Concilium
Constitution on the Sacred Liturgy
article 104

"The Church has also included in the annual cycle days devoted to the memory of the martyrs and the other saints. Raised up to perfection by the manifold grace of God, and already in possession of eternal salvation, they sing God's perfect praise in heaven and offer prayers for us. By celebrating the passage of these saints from earth to heaven the Church proclaims the paschal mystery as achieved in the saints who have suffered and been glorified with Christ; she proposes them to the faithful as examples who draw all to the Father through Christ, and through their merits she pleads for God's favors."