The Songs In My Head Get Nerdier.

I give you these Belle & Sebastian lyrics:

The bourgeoisie, historically,
Has played a revolutionary part
To end all feudal, idyllic relationships.
It has resolved personal worth,
And in place of freedom
Is exploitation for profit alone.
There is a spectre of the past
In my bold assertion.
We could learn much from the past.

Bonus nerd points if you can tell me what leftist political tract is being paraphrased here.