Blessings come under the category of sacramentals. A sacramental is a special prayer, action, or object which, through the prayers of the Church, prepares a person to receive grace and to better cooperate with it. For example, we make the sign of the cross using Holy Water when entering a Church: That pious action and the Holy Water itself, which together remind us of our Baptism, awaken us to the presence of God and dispose us to receiving God's grace. Unlike a sacrament, a sacramental does not itself confer the grace of the Holy Spirit. Nevertheless, like a sacrament, a sacramental helps the faithful to sanctify each moment of life and to live in the Paschal mystery of our Lord.
Among the sacramentals, blessings would be foremost. In the decree publishing the Book of Blessings, Cardinal Mayer, then prefect of the Congregation for Divine Worship, wrote, "The celebration of blessings holds a privileged place among all the sacramentals created by the Church for the pastoral benefit of the people of God. As a liturgical action, the celebration leads the faithful to praise God and prepares them for the principal effect of the sacraments. By celebrating a blessing, the faithful can also sanctify various situations and events in their lives." Blessings are signs to the faithful of the spiritual benefits achieved through the Church's intercession.
Throughout Sacred Scripture, we find how God issued various blessings: In the Genesis account of creation, God blessed all the living creatures and especially Adam and Eve, telling them to be fertile, to multiply, and to fill the earth and subdue it (cf. Genesis 1:22, 28). After the flood, God blessed Noah and his sons (Genesis 9:1ff). The patriarchs administered blessings, particularly to the eldest son, signifying a bestowing of God's benevolence, peace, and protection. In a similar vein, the Lord spoke to Moses and commanded the following blessing for all the Israelites: "The Lord bless you and keep you! The Lord let His face shine upon you, and be gracious to you! The Lord look upon you kindly and give you peace!" (Numbers 6:22-27). The people also blessed God, praising His goodness shown through creation, as illustrated in the beautiful hymn of praise in the Book of Daniel (3:52-90). The Preface for Eucharistic Prayer IV captures well this understanding of a blessing: "Father in Heaven…, source of life and goodness, you have created all things, to fill your creatures with every blessing and lead all men to the joyful vision of your light."