The Durban strikes of 1973 empowered workers and helped destroy apartheid.
This month 40 years ago, South Africa learned an important truth which shaped our future - that people without power can challenge those who have it, but only if they act together.
The lesson was taught by the Durban strikes of 1973; they began a process which shifted power to working people and played an important role in defeating apartheid.
First, the strikes triggered the formation of unions which fought long battles with a few employers to win the right to negotiate. These unions became the core of the Federation of SA Trade Unions which combined with other unions to form Cosatu in the mid-1980s. So they were, in a sense, the beginning of today's union movement.
Second, while many histories see the 1976 Soweto uprising against Afrikaans as the beginning of the end for apartheid, the Durban strikes may have been the turning point.
Previous strikes by black workers had been crushed - the 1973 strikes led to wage increases. Instead of relying only on force, the state tried to use reforms to appease workers. Firms had begun to rely on black workers to do semi-skilled work previously reserved for whites because there were not enough white workers to go around. Because black workers had more skills, they could not be replaced easily.
The government's plan was to allow blacks a voice but no power: committees in the factories could discuss their grievances - it hoped this would avoid the need to deal with unions with a right to strike. But the reforms simply opened new avenues for resistance - by the end of the 1970s the government extended bargaining rights to unions.
While these rights came with restrictions which were meant to hamper strikes and political activity, the new union movement became a centre of militancy which soon joined the fight against apartheid.
This pattern soon spread. In the face of growing anti-apartheid militancy, the government tried reforms which aimed to soften apartheid's effects while keeping white political domination in place.
But each reform opened up more avenues for resistance and weakened apartheid further. The migrants who refused to live in single-sex hostels in the Western Cape and erected shacks in the townships helped to end the pass laws which barred black workers from living with their families in the cities, while student and township militancy in the 1980s ensured that reforms weakened apartheid. And, as the last battle of the apartheid era was waged in townships and shack settlements, the union movement was a key source of support to the fight for change. In many townships, some of the methods used by unions inspired activists and influenced their fight for rights.
So the events this month 40 years ago in Durban changed the face of South Africa - the democratic Constitution achieved in 1994 was a consequence of processes set in motion then: they began a government retreat and helped build the organisations and style of organising which turned that retreat into a defeat.
In the process, unionism gave working people a voice and built a social movement. The more people without power work together to gain small changes, the more confident they become and the more likely are they to feel strong enough to demand bigger changes. The union movement is evidence - surveys show that union members tend to expect more change than other citizens.
Why all this history? It has become fashionable to insist that our current realities show that the promise of empowering people, forged in the struggle against apartheid and enshrined in the Constitution, has not been realised.
The Western Cape farm strikes and the Marikana shootings are quoted as examples which prove how little progress we have made. But the history of the union movement places this in perspective.
Developments in the workplace since 1994 have not disappointed the hopes which were kindled by the 1973 strikes. Working people who belong to unions today have a voice and their conditions are far better than those against which the Durban strikers rebelled.
The union movement has made many mistakes and has fallen prey to the same temptations as the ANC - union posts are often a route into the middle class, not a means to serve workers. But the movement remains the largest and most influential in the country today. As the surveys mentioned earlier show, the early strikers and unionists also built a social movement in which people have distinct attitudes which make them more likely to insist on their rights.
Our problem today is not that the union movement failed. It is, rather, that the organisation which enabled people to act together to change their lives is not yet deep or broad enough.
Its lack of depth means that, in some industries, union members do not have the power over their organisation which many others do - this caused the conflict which led to Marikana. Its lack of breadth means that farm and domestic workers, for example, still lack the organisation which those in the factories, shops and offices enjoy - this is one cause of the troubles on the farms.
It means also that the organisation which workers enjoy is not available to many outside the workplace - in townships and shacks and rural areas.
This is why the voice of the poor is not heard in our debates and why, for the past nine years, people have been taking to the streets in townships and shack settlements to express their frustrations.
Organising people in neighbourhoods needs different methods to those the unions use.
But the principle remains the same - when people find ways to get together to gain a voice and to win small changes in their lives, big things can begin to happen.
The history which began in Durban 40 years ago should inspire us - to find ways in which everyone can enjoy the power to organise effectively.