The Offertory
Before the gifts can be taken, something must be offered. Therefore, after the Universal Prayer closes, a collection is taken as part of the offertory. In the early Church, it would be common for people to bring the fruits of their labors: produce, oils, animals, etc. These days, the fruits of most people’s labor is money, so rather than give the actual products, money is given to provide for those products.
The reasons for the people giving was --and is-- in the words of canon 1254,
Are principally the regulation of divine worship, the provision of fitting support for the clergy and other ministers, and the carrying out of works of the sacred apostolate and of charity, especially for the needy.
There are occasional second collections during the year, as designated by the diocese.
It is the custom that a congregational song be sung at this time. This is an optional practice. Other options are: a song by the choir, an instrumental piece, or silence.
While giving to the collection is practical—it helps keep the church lights on (!)—it also has a symbolic meaning. Giving of one’s resources is a sacrifice. Our giving at the offertory is joining our sacrifice with the sacrifice of Jesus to be offered in the Liturgy of the Eucharist. Our giving is symbolic of our giving of our labors, trials, and struggles; our joys, hopes, and desires; and of our bringing our secular lives and works to the Lord. As the gifts of bread and wine are given and transformed and given back to us, when we give our lives to the Lord, He will bless and transform them and give them back to us—along with Himself. In doing so, He lifts our burdens, redoubles our joys, and goes with us into our work and lives so that we may proclaim Him even there.
I also see the collection as a link between the Liturgy of the Word and the Liturgy of the Eucharist. As we prayed for the needs of the Church in the Universal Prayer, in giving to the collection we are “putting our money where our mouth is” and providing the resources for those needs.
