“Only the future can provide the key to the interpretation of the past; and it is only in this sense that we can speak of an ultimate objectivity in history. It is at once the justification and the explanation of history that the past throws light on the future, and the future throws light on the past.”

Thucydides wouldn’t have put it in that way, but I suspect this is what he meant when he encouraged his readers to seek “knowledge of the past as an aid to the understanding of the future, which in the course of human things must resemble if it does not reflect it.” For without some sense of the past the future can be only loneliness: amnesia is a

So why study history? Unlike physics or economics, history is not a means for making accurate predictions. We study history not to know the future but to widen our horizons, to understand that our present situation is neither natural nor inevitable, and that we consequently have many more possibilities before us than we imagine.

That’s a theoretical argument. An observational argument is that we know that the technological innovation of the Renaissance began by rediscovering history. And we know that the Founding Fathers cared deeply about history. In both cases, they stepped forward by drawing from the past. So if you’re a technologist looking to blaze a trail with a new

Learning of historical precedent as well matters little, since we don’t learn in the same way from description as we do from experience. It’s something known as the description-experience gap.

The test of a good theory lies in its ability to explain the past, for only if it does can we trust what it may tell us about the future.