Probably no more than a half-dozen books have singly influenced my thinking as much as has Harold Berman’s 1983 classic, Law and Revolution : The Formation of the Western Legal Tradition . I was very sad to learn that Professor Berman died a few days ago .
In the early 1990s I spent several days with Prof. Berman and his charming wife at an Institute for Humane Studies  seminar in Belmont, CA. Organized by Leonard Liggio, the general subject of the seminar was the nature and origin of law. Law and Revolution was the centerpiece of the readings. And what a treat it was to have Harold Berman actively participating in all of the discussions! I remember him as being deeply scholarly — a man possessing as complete a command of his subject as is humanly possible and yet, simultaneously, unfailingly curious about different perspectives and open always to the possibility of changing his mind should he encounter sufficiently compelling facts or arguments.
Harold Berman was also genuinely kind, without a hint of pretentiousness.
The main lesson of Law and Revolution is that law can — and certainly did in western Europe — emerge unplanned from competition among different wannabe sovereign powers. During the middle-ages and early modern era the Roman Catholic church sought absolute sovereignty. So too, did various princes. And these seekers of unalloyed sovereignty each had to compete for authority not only with each other, but also with the law-making processes that emerged in cities, on feudal manors, and — importantly — among merchants.
Sovereignty in the west, fortunately, was fractured. The competition for absolute power — the quests of the princes and of the church, of "caesar" and of "christ," each to wield absolute power prevented either of them from becoming absolute. Competition is a grand thing. And law is not so much the product of a sovereign, or of a law-giving genius, as it is the emergent outcome of countless instances of human interactions  and struggles of each of us and of those who would rule us to carve out elbow room for ourselves and domains of authority.
I’ve yet to read the follow-up volume  to Law and Revolution. I’ll do so soon.