The period of which this volume treats differs fundamentally both from that which precedes and from that which follows it. In each of those periods we are able to fix our attention upon a certain well-defined set of institutions which completely control its activities. In the former, the strictly mediĂŚval, we see Europe wholly under the sway of two vast ideas, feudalism and the Roman church system. In the latter, the purely modern period, Europe has almost wholly lost those ideas and has come out into the familiar political structure of a family of independent national states and into the freer air of religious toleration, if not yet of religious liberty.