I am aware that some will be at a loss to account for my interrupting the course of my narrative for the sake of entering upon the following disquisition on the Roman constitution. But I think that I have already in many passages made it fully evident that this particular branch of my work was one of the necessities imposed on me by the nature of my original design; and I pointed this out with special clearness in the preface which explained the scope of my history. I there stated that the feature of my work which was at once the best in itself, and the most instructive to the students of it, was that it would enable them to know and fully realise in what manner, and under what kind of constitution, it came about that nearly the whole world fell under the power of Rome in somewhat less than fifty-three years,—an event certainly without precedent. This being my settled purpose, I could see no more fitting period than the present for making a pause, and examining the truth of the remarks about to be made on this constitution. In private life if you wish to satisfy yourself as to the badness or goodness of particular persons, you would not, if you wish to get a genuine test, examine their conduct at a time of uneventful repose, but in the hour of brilliant success or conspicuous reverse. For the true test of a perfect man is the power of bearing with spirit and dignity violent changes of fortune. An examination of a constitution should be conducted in the same way: and therefore being unable to find in our day a more rapid or more signal change than that which has happened to Rome, I reserved my disquisition on its constitution for this place.... What is really educational and beneficial to students of history is the clear view of the causes of events, and the consequent power of choosing the better policy in a particular case. Now in every practical undertaking by a state we must regard as the most powerful agent for success or failure the form of its constitution; for from this as from a fountain-head all conceptions and plans of action not only proceed, but attain their consummation....