"Erst kommt das Fressen, dann kommt die Moral" declare both Macheath and Jenny in the ballad "Wovon lebt der Mensch" in Bertolt Brecht's Die Dreigroschenoper. Like you, I suppose, I've quoted this phrase many times as a profound truth. Now I wonder whether even Brecht believed it -- he puts it into the mouths of two of his most rascally characters. More to the point, I'm wondering if it's even historically correct: that people have been concerned about getting their grub, and only then attending to their spiritual needs.
I've been pondering the archaeological evidence from ancient Peru and from work I did earlier on the ancient civilizations of Mexico and Guatemala, from the Olmecs to the Mexicas (Aztecs). Just now I was trying to make sense of the temple and sculptural remains of Chavín de Huántar, an imposing power center that flourished from some time before 500 BC to about 200 BC, in the northern highlands of Peru. It seems clear that the most impressive architecture, representing by far the greatest collective effort, was performance spaces for sacred rites (such as a priest's turning himself into a jaguar, for example). By spreading their jaguar religion, the people of Chavín (or at least their rulers) spread their power and trade. That is, first came the missionaries, then came the merchants.
But Macheath's dictum, "First comes the grub, then the morality," is not just a cynical gangster's way of belittling morality. It is also a central tenet of modern liberal thought, the pragmatic view that used to be dominant in the U.S. First we need to take care of people's material needs, including food, shelter, health care, etc. Then we can argue about mystical and religious matters if we like. That's what every progressive (or Progressive) American used to believe. Now I think it's very unfortunate that we have an administration that wants to push us back to the mentality of the jaguar priests: "First comes Holy Scripture, then comes Haliburton."
Here's a discussion of the "First comes the grub..." phrase from The Threepenny Opera, in everything2. You can get info and see a terrific video on Chavín de Huántar at The Global Heritage Fund site.