Same here. I "aha" at the
lamb brain in paper bag. I wonder where do they cook such meal. It's odd
for the waiter to earnestly recommend such meal to someone who doesn't
understand "lamb brain" in that language.
More odd is that after the people know that's lamb brain, they laugh
and drink red wine without too much thought of the brain on their table.
I think this is the main theme of the poem, "We are the creatures
that love and slaughter." (last line)