It can be hard to look back and choose a beginning. Especially for an evolving story. Here is one beginning.

In 326 BCE, on the banks of the Beas River in what is now the Punjab, Alexander of Macedon encountered a small group of naked philosophers. Alexander was at the furthest point of his journey east — not yet turning back, not yet broken, balanced at the apogee of everything he had set out to do. He had been tutored by Aristotle and had carried the Greek intellectual inheritance across Persia, Egypt, and Bactria. He had conquered the known world. And now, at the edge of it, he found men who had renounced everything he had fought for.

What passed between them cannot be known with certainty. Ancient sources give us fragments: an exchange about philosophy, about the nature of kingship, about the difference between a man who had everything and men who wanted nothing. Something accumulated in that encounter — a grain of something that would travel west, passing through the Stoics, through the early Christians, through centuries of transmission and translation and transformation, until it arrived, changed beyond recognition and yet recognisably itself, in the liberal democracies we inhabit now.

That chain of transmission is what this book is about. Not Alexander, and not the gymnosophists, and not the Stoics — but the process by which ideas enter a mind, are changed by what they find there, change in turn what they find, and then leave a trace that continues long after the mind itself has stopped.

The self is not a thing. It is a process. Put another way: it is the time-integral of lived moments. Identity is not a noun; it is a curve.