"There is no such thing as society. There are individual men and women, and there are families," she said in an interview with Woman's Own magazine in October 1987.
Although she had merely been talking about the need for people to stand on their own two feet rather than relying on the state for handouts, the comment swiftly gained a life of its own.
And while it initially captured the late-80s zeitgeist, in time it came to be seen as part and parcel of the "nasty party" image that the Tories fought to shake off during their wilderness years.
At one level, the 'Big Society' was to David Cameron what 'New Labour' was to Tony Blair – a marketing slogan whose main purpose was to detoxify a brand that had become tarnished.
Its aim was to demonstrate that not only did the Tories now believe in society after all, they actually had a vision for the kind of society they wanted to create.
But whereas New Labour had a genuine philosophical basis - the embracing of the Thatcherite economic consensus and the abandonment of 'tax-and-spend' - the Big Society has always been much harder to pin down.
Tory candidates reported it had caused bemusement on the doorsteps during last year's election campaign, a state of affairs not helped by the fact that many of the candidates were similarly bemused themselves.
In government, the more urgent question has become less about what the Big Society is, and more about whether it is compatible with the kind of policies the Coalition is pursuing.
Liverpool City Council thinks not. It pulled out of a Big Society pilot project this week on the grounds that it is not deliverable in the context of £91m budget cuts and 1,500 job losses.
Although the Labour-run authority was swiftly accused of gesture politics, it is self-evident that it is hard to sustain local community activities and initiatives if the funding that underpins them disappears.
The closure of large numbers of Citizens' Advice Bureaux as a result of town hall cutbacks is surely a case in point here.
The wider problem with the 'Big Society, though, is not so much whether it is compatible with reductions in public expenditure as to whether it is compatible with free market economics at all.
Will our forests, for instance, end up in the hands of cuddly 'Big Society-ish' institutions like the Woodland Trust or other local community groups, or will they all simply be sold to the highest bidder?
Will local people really be able to club together to buy and run their failing village pub when the brewery is being offered ten times as much by a developer who wants to knock it down and build ten flats on the site?
It is for these sorts of reasons why people would not necessarily regard the Big Society and the Tory Party as the most natural of bedfellows.
Mr Cameron may be a skilled PR man, but to regard the Big Society as no more than a piece of spin is probably to do him a disservice.
He passionately believes in it, even if he sometimes struggles to articulate it in a way that the voters can relate to, and would probably like his government to be remembered for it above all else.
The great historical irony about the Big Society is that at the time Margaret Thatcher came out with her infamous quote, there was actually much more of one than exists today.
It will take much more than words if Mr Cameron is somehow to recreate it.