Bourgeois morality arise from arbitrary conventions rather than eternal verities.

Claiming that a Wall is immoral is asinine for norms of bourgeois morality arise from arbitrary conventions rather than eternal verities.  The Greeks had slaves and so did some of the founding Father of the US.

In those epochs slavery was not considered to be bad, the Greeks deemed it as good
so there was no eternal moral verity, that slavery was eventually deemed as 'bad' arose out of an 
in the first instance, an arbitrary convention.