The Sacraments are a wonderful gift of God to men. Through them, the power of Christ's Passion is applied to the souls of men for their salvation. Through the sacraments men are reborn and remade into the likeness of Chirst. Through the sacraments men become the children of God and the heirs of Heaven. Because they are effective signs of grace which they signify, they give men an easy way to obtain the grace of God. They are another tender sign of God's mercy. He has not left men to wonder whether or not they have obtained the grace of God or can obtain the grace of God. In the sacraments, God has given men a sure way of obtaining His grace. The sacraments are the visible signs of God's love for men. 

-My Way of Life Pocket Edition of St. Thomas
Walter Farrell, O.P.,S.T.M. & Martin Healy, S.T.D.