Just as the leaves change on the trees to mark time, so the Mass changes–subtly–throughout the year to reflect the different times and seasons.
The Scripture readings in the lectionary are keyed to the festivals and seasons. They reflect the events we celebrate. Some of the prayers change in a similar way. There are special versions to match the changing times and changing themes. Some of the Eucharist Prayers allow for different insertions during the holy seasons.
During the seasons of Advent and Lent–which are seasons of penance and preparation–we suppress the jubilation of the Gloria; and during Lent we suppress the Alleluia as well.
The central events of our salvation take place in history, at specific times and in particular places. So we Christians have developed a highly refined way of marking the passage of time, keeping the life of Jesus Christ always before us.
Excerpted from The Mass by Cardinal Donald Wuerl and Mike Aquilina. Copyright © 2011 by Archbishop Donald W. Wuerl. Excerpted by permission of Image, a division of Random House, Inc. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.