score:4
The basic idea is that of "smiting oneself." As Howard Marshall puts it, commenting on Luke 18:13:
The breast or heart is regarded as the seat of sin, and hence the act is one of grief or contrition.1
As alluded to here, in the Hebrew background of the expression lies the word for "heart" (Heb. leb or lebab). Nahum 2:7 is a good example:2
... her slave girls lamenting, moaning like doves, and beating their breasts (lit. hearts)
In the Old Testament, the leb is the affective, noetic, and ethical center of a person. Inflicting blows to it, then
expresses a sense of diminution ... it is an act of self-abas*m*nt to influence the deity.3
Whereas leb has no specific anatomic referent,4 the reflex Greek translation for the abstract leb is kardia. Like leb, kardia is very frequently used metaphorically, but where there is a concrete referent, it is clearly the organ we know as the heart. It may be for this reason that in the Greek expression we find instead stēthos ("breast"), a part of the body more accessible for beating.
Notes:
This question has also been asked on the English Language and Usage site. To me, the specific Biblical evidence is worthwhile considering in addition to the general conclusions stated there.
1. I. Howard Marshall, The Gospel of Luke: A Commentary on the Greek Text, NIGTC; (Eerdmans, 1978), p. 680.
2. The OP offers Isaiah 32:12, which may indeed carry a similar sense, but the Hebrew is a bit obscure: "mourning on breasts", so not actually an explicit example of "beating".
3. Heinz-Josef Fabry, "לֵב לֵבָב," TDOT, (Eerdmans, 1972) v.7, p. 411.
4. In the minority of usages (such as this) involving a concrete part of the body, it sees to be located in the area of the thoracic cage, but it is not clearly the heart. See Fabry, TDOT, for extended discussion.
Upvote:0
I think it is a reflexive action of the human body. When one is in a terrible stage of sadness or shock, one is prone to lose breath. Manual pressure on the heart, as is done in resuscitation of victims of heart attack, helps pump more air into the lungs and keeps one alive.
As for children, it is just one of their tricks to attract the attention of their parents!