Bread is the great re-enforcer of the reality principle. Bread is life. But if you're like me you have a thousand and more times repeated the ordinary experience of eating bread without a thought for the process that brings it to your table. The reality is physical: I need this bread to live. But the reality is also social: I need others to provide the bread. I depend for bread on hundreds of people I don't know and will never meet. If they fail me, I go hungry. If I offer them nothing of value in exchange for their loaf, I betray them. The people who grow the wheat, process and store the grain, and transport it from farm to city; who bake it, package it, and market it—these people and I are bound together in an intricate reciprocal bargain. We exchange value.
I'm a very lucky person with every allergy known to man but still happy to be enjoying a wonderful life living in the best place in the world!