There's a powerful myth, promulgated by Tony Blair, by the Tories, by most of the media. It is that businessmen are 'wealth creators'. Without them, we're told, there would be no investment, no jobs, an economy in a spiral of decline.
Under feudalism, using the same logic, without the lords there would be no land. The peasants would just float in the air, starving.
What is true in current-day society is that the means of wealth creation are in the hands of a small class of capitalists. They own and control the major means of production-the factories and offices, the roads, railways, docks and airports, and so on.
Often - indeed increasingly, through 'privatisation' - they own them privately. Sometimes nation-states own them. In either case, access to and decision-making control over these facilities is out of the hands of the mass of the population.
What about the rest of us? A minority still own the means to make a living-small farmers and shopkeepers, the self employed, independent craft workers. The old term for these is the 'petty bourgeoisie'. A few of them earn quite well, but most scratch along putting in long hours and earning no more than average wages. Often, they move in and out of the working class.
The majority - the working class - can only make a living if they work for someone else, in return for a wage or salary.
The working class are the key wealth creators. They produce most of the goods and services society needs - in workplaces that they neither own nor control.
In principle it makes no difference whether they work for private corporations or the state. In either case, they work under bosses they don't choose, and they earn only enough to live from one month to the next.
As every slave knew, being a wealth creator doesn't make you wealthy. The goods and services that workers produce belong not to them, but to their bosses. In the very process of producing things, the working class also reproduces the wealth of the capitalists.
Microsoft workers don't just develop software, they also develop Bill Gates's immense riches, and his power over themselves. Workers' daily activity under capitalism reproduces the ruling class, its profits and its control.
That's what the term 'exploitation' means. Workers produce vast surpluses, which end up in the hands of those who rule over them, in the economy and in the state alike. The more they work, the richer and more powerful their exploiters become.
Capitalism is a system that depends on this daily robbery, carried out in every workplace every minute of every day. At its heart is the activity of the working class.
The working class, in this crucial sense, has continued to expand as capitalism has developed across the world.
At the time that Marx and Engels wrote The Communist Manifesto, back in 1848, the working class was still a tiny proportion of the world's population, chiefly concentrated in a few countries in Western Europe.
Today, the working class in just a small country like South Korea is probably bigger than the world's working class a century and a half ago.
Sometimes you hear it argued that the working class is shrinking, because 'manual work' is declining.
What a weird argument! 'Manual' means 'by the hand' - but somehow it's supposed the nurses and computer operators, people in offices and call centres don't need hands! It's not the colour of a person's collar that determines their class, but their relationship to the means of production.
Nor do consumption patterns determine class. If they did, then we'd have to agree with the 19th century Lancashire commentator who sighed that the working class was disappearing because shoes were replacing clogs!
Capitalism is the most dynamic system of production in history, and it constantly changes the make-up of its own workforce.
In 19th century Britain the biggest sources of employment were agriculture, textiles and coal. As they shrank, the metal trades grew. In turn, these have been partially displaced by new, electronics-based industries. But the changes haven't meant the working class has shrunk-it's continued to grow.
As the key exploited class in capitalism, the working class also possesses immense potential power, not just to halt capitalist production, but to transform society. That power is the key to the possibility of socialism.
We have launched this column in response to question from readers at meetings organised across the country.