St. Augustine, in his Enarrationes in psalmos 117, speaks of the thunder-like sound, strepitus, made in church by the beating of breasts at the mention of the word confessio:
Audivimus, fratres, admonentem nos atque hortantem Spiritum sanctum, ut sacrificium confessionis offeramus Deo. Confessio autem, vel laudis eius est, vel peccatorum nostrorum. Et illa quidem confessio, qua peccata nostra Deo confitemur, omnibus nota est; ita ut hanc solam dici confessionem in Scripturis sanctis minus erudita existimet multitudo: nam ubi hoc verbum [i.e., “confessio”] lectoris ore sonuerit, continuo strepitus pius pectora tundentium consequitur. Sed debent advertere quomodo dictum sit in alio psalmo: Quoniam ingrediar in locum tabernaculi admirabilis usque ad domum Dei, in voce exsultationis et confessionis, soni festivitatem celebrantis. Hic enim certe manifestum est vocem confessionis et sonum, non ad moerorem poenitentiae, sed ad laetitiam festivitatis celeberrimae pertinere.
My brothers and sisters, we have heard of the Holy Spirit admonishing us, exhorting us, to offer a sacrifice of confession to God. Now confession can be either an offering of praise or an acknowledgment of our sins. Confession of sins is something familiar to everyone; indeed we are so used to it that when the holy scriptures mention confession, the majority of less educated people think it always means that. As a result, no sooner has the word been uttered by the reader than a devout din follows: the sound of people striking their breasts. But they should remember what is said in another Psalm: I will walk into the wonderful attempt, even to the house of God, amid the shouts of joy and confession and the sound of people celebrating a festival (Ps 41:5 (42:4)). It is quite obvious from that Psalm that the songs and sounds of confession are signs not of penitential grief but of a joyful and very crowded festival. (trans. Maria Boulding, OSB)
I would not choose “din”, which has a tinny quality to it. Better would “rumble” or “thunder”.
Now that I have, I hope, whetted your appetite, check out a good post at NLM about breast beating and then …
GO TO CONFESSION!
In the NLM piece, the writer, Peter Kwasniewski quotes Dom Cassian Folsom of Norcia who, in turn, quotes Roman Guardini about the beating of breasts. Folsom and Guardini reinforces Augustine’s point: the moving sound of the beaten breast and its… ehem… personal impact. Here’s a sample (emphases mine):
Fr. Cassian continues, quoting one of my favorite books, [Romano] Guardini’s Sacred Signs:
Guardini has something to say about this gesture too. He asks the question: “What is the significance of this striking the breast? All its meaning lies in its being rightly done. To brush one’s clothes with the tip of one’s fingers is not to strike the breast. We should beat upon our breasts with our closed fists. In the old picture of Saint Jerome in the desert he is kneeling on the ground and striking his breast with a stone. It is an honest blow, not an elegant gesture. To strike the breast is to beat against the gates of our inner world in order to shatter them. This is its significance.” … The gesture of striking the breast, made carefully and with full awareness, can communicate to ourselves and to others more than mere words can say, that we recognize our sinfulness and publicly declare our sorrow for our sins. … Try it yourself. The rib cage is like an echo chamber. If you strike your breast properly, you’ll hear the sound of it: like the sound of thunder.
Tracking back to Augustine, the act of striking one’s breast in acknowledgement of sin is not just a signal of sorow. For the Christian, it is also a gesture of freedom, a sign of hope.