A commentator to my previous posting claims that the interpretation I give is not based on the literal meaning of the psalm, but only on an allegorical one, and he makes an appeal to St. Thomas Aquinas for a teaching that the sense of Scripture must always be based on the literal.

It is certainly true that a correct sense of Scripture has to be based on the literal meaning. But first we have to clear up exactly what is meant by the literal meaning (especially since "literal" is often given a distinctly unhelpful meaning in non-Catholic circles). The literal meaning is simply the meaning intended by the author. For example, if an author makes the statement: "On the fourteenth day of the first month the returned exiles kept the passover", then (in the absence of any particular argument that it refers only to some hidden metaphorical meaning) we should make the interpretation that the author was simply recounting an historical fact, and that this historical fact is the literal meaning of the text. More interestingly, if an author says: "You shall remember that you were a servant in the land of Egypt, and the LORD your God brought you out thence with a mighty hand and an outstretched arm", then since we do not think that God actually extended some giant physical hand and arm in order to rescue Israel, we see the author's intended meaning as a reference to the power God exerted in order to rescue Israel. In other words, the literal meaning of the author is that God exerted power, and not that God used some large physical hand. The author is expressing his literal meaning in a metaphor.

This is what Thomas Aquinas is referring to when he says: "The parabolical sense is contained in the literal, for by words things are signified properly and figuratively. Nor is the figure itself, but that which is figured, the literal sense. When Scripture speaks of God's arm, the literal sense is not that God has such a member, but only what is signified by this member, namely operative power."

Given that, let us now go through Psalm 137 looking for the author's intended meaning — which is to say, the literal meaning: "If I forget you, O Jerusalem, let my right hand wither!". Does the author really intend that only precisely and exactly his right hand withering is the correct punishment, such that no other punishment could possibly be correct — so that his left hand withering would be meaningless, or becoming deaf would not be an appropriate punishment at all? Or does he use the reference to right hand as a metaphor standing for something highly personal and valuable. Surely "right hand" is used as a metaphor; so that the intended meaning of the author is literally that an appropriate punishment for forgetting Jerusalem should be that he lose something personal and valuable. Similarly, when the author says: "Let my tongue cleave to the roof of my mouth, if I do not remember you" this is again intended metaphor. The literal meaning is something like: "If I forget the home God gave us, may I never be able to speak of anything at all".

So, the author of the psalm is giving examples (i.e. metaphors) of punishments, and not precisely definitive statements.

Given that the author is already using examples and metaphors to express his meaning in the previous verses of the psalm (and after all this is plainly a very common thing to do in the psalms), we then have cause to read the last part of the psalm very carefully indeed. Should we take the details given as being precisely intended, or as intended example referring to an appropriate punishment for those who helped in the downfall of Jerusalem? As an example, not as a precise definition.

When the author of the psalm calls for a particular punishment for the Edomites, is he giving exact and precise physical details of the only possible way in which the appropriate punishment can be applied? Does the author intend to give the only way? No. After all, if we asked the author: "Suppose one of the guilty Edomites actually hated his own child, would it be an appropriate punishment for him to have his child dashed against the rocks?", I really cannot suppose that the author would say, "Oh, in that case he should escape punishment completely." But I do think that if the author were asked: "Suppose a guilty Edomite hated his own child, but had spent his whole life working at his business earning riches, would it be an appropriate punishment for him to have his business and wealth utterly destroyed in front of his eyes", that the author would agree with the punishment.

At the end of the psalm, the author is giving an appropriate punishment, but not the only possible appropriate punishment. In which case, the author is using an example to stand for a range of other things. Which is what metaphor is. So, when my interpretation relies on many things being our children, and not just our physical children, I do not think I have stepped away from what the original author intended — which is to say, I have not stepped away from the literal meaning of the text.