Status Updates From Value, Price and Profit

May be a better introductory read for Marx's Labour theory of value the 'Wage Labour and Capital', though I'd still recommend reading both. You only need to read chapters 6-12 as far as I'm concerned, if your copy has the whole speech.

The rest of these pages focus workers ideals, making concise points about the economics of particularly the valuation of labor. While workers already create more value than they are paid to create capitalist profit, idea of "surplus value" he also claims the word profit itself can only exist from exploiting the worker or taking advantage of the customer, which is objectively wrong, no matter how subjectively ethical.