They become all body and no mind -- powerless

[This was my letter to John Langdon, March 5, 1810, where I explained the natural degradation of the monarchical state, and thus why Napoleon Bonaparte was able to conquer Europe.]

Take any race of animals, confine them in idleness & inaction whether in a stye, a stable, or a stateroom, pamper them with high diet, gratify all their sexual appetites, immerse them in sensualities, nourish their passions, let every thing bend before them, & banish whatever might lead them to think, & in a few generations they become all body & no mind: & this too by a law of nature, by that very law by which we are in the constant practice of changing the characters & propensities of the animals we raise for our own purposes.

Such is the regimen in raising kings, & in this way they had gone on for centuries. While in Europe, I often amused myself with contemplating the characters of the then reigning sovereigns of Europe. Louis the XVIth was a fool, of my own knowledge, & in despite of the answers made for him at his trial. The king of Spain was a fool, & of Naples the same. They passed their lives in hunting, & dispatched two couriers a week, 1000 miles, to let each other know what game they had killed the preceding days. The king of Sardinia was a fool. All these were Bourbons. The Queen of Portugal, a Braganza, was an idiot by nature. & so was the king of Denmark. Their sons, as regents, exercised the powers of government. The king of Prussia, successor to the great Frederic, was a mere hog in body as well as in mind. Gustavus of Sweden, & Joseph of Austria were really crazy, & George of England you know was in a straight waistcoat. There remained then none but old Catharine who had been too lately picked up to have lost her common sense. In this state Bonaparte found Europe; & it was this state of its rulers which lost it with scarce a struggle. These animals had become without mind & powerless: and so will every hereditary monarch be after a few generations.