Editor's Note: Alison Wolf is the author of The XX Factor: How the Rise of Working Women Has Created a Far Less Equal World. A British academic and journalist, she is currently the Sir Roy Griffiths Professor of Public Sector Management at King’s College, London and she also advises the UK government on education policy. Here, as part of Biographile's Lessons Learned month, a month of authors sharing lessons they've learned while writing their book, Wolf shares her thoughts on how even the smallest changes can impact the greater social landscape. If each century is marked by its differences, then those differences alter people's expectations and values.

We all cherish our individuality: It's why ‘I’ll Do It My Way’ is the most-covered song ever. We are fascinated by family and family history. But the twenty-first century Western world through which we swim? That, too often, we treat like a fish does water: it’s normal, a given.

Writing The XX Factor taught me to see our world as strange and new, and also to feel, quite viscerally, how it shifts and changes around us. It’s a book about the impact on the world of seventy million educated professional high-earning women, a number which is huge and completely unprecedented. When I first proposed writing it, I said that society’s tectonic plates had shifted: this is an earth-changing event. I still think that.

But I’m also now far more aware of the constant small changes in how we live, and of how, unremarked at the time, they transform our social landscape. Who would have thought, for example, that pizza deliveries were a revolution in the making? But they were. The small changes make the big ones possible -- and they also go on and on.

And what writing this book also taught me, as I dug into the last few centuries, is that, in our ever-flowing society, it really matters when you step in. It really matters when you were born.

This probably sounds banal. Obviously, it was a bad idea to be a woman anywhere before the late nineteenth century if you wanted to have a vote. Obviously, young men called up in 1914, or 1917, drew a very short straw along with their birthdate. But it is more than that. It is not just about what happens to you. It is about the sort of person you are.

Different periods form people differently. Reading people’s own words from across the centuries, brought home how differently they saw and experienced life. We tend to feel sorry for educated women of the nineteenth and early twentieth centuries, with their restricted career choices. But they had very different values -- I’m tempted to say better ones: they really believed in a life of service to others, and in duty. They were genuinely different. Should we assume that they were wrong?

Because values, and assumptions develop and fall away quite slowly, we’re hardly aware of how different we are from previous generations. Or, indeed, our younger selves. I would love to meet myself at ten, or fifteen and find out how I saw things then. Because I was born on the cusp of generational change – something else I only fully realized in writing The XX Factor.

Things I take for granted were, it turned out, still very uncommon in my teens and twenties; values and beliefs which are now global and globally potent were still new. Talking to older friends, they remark on how much of what I describe, which has become standard, was not true before the 1970s. What did I believe then? I can’t know, not really. But perhaps my and other people’s children will re-read this book in forty years’ time and feel the departed world of 2013 stir back into life.

For all Lessons Learned articles, visit the archive here.