One class privately own lumber forests and marble quarries, and buy labor-power;

The other class work in the lumber forests and marble quarries, and sell labor-power.

One class privately own cotton mills, steel mills, and flour mills, etc., and buy labor-power.

The other class work in cotton mills, steel mills, and flour mills, etc., and sell labor-power.

One class privately own railroads and buy labor-power;

The other class work on railroads and sell labor-power.

Or, to say it briefly,

One class, the capitalist class, privately OWN the chief material means of production—and BUY labor-power.

The other class, the working class, USE the chief material means of production—and SELL labor power.

Surely you can see that there are two industrial classes.