History of Friedrich II of Prussia, Volume 11 by Thomas Carlyle

At Wesel, in the rear of all this travelling and excitement, Friedrich falls unwell; breaks down there into an aguish feverish distemper, which, for several months after, impeded his movements, would he have yielded to it. He has much business on hand, too, -- some of it of prickly nature just now; -- but is intent as ever on seeing Voltaire, among the first things. Diligently reading in the Voltaire-Friedrich Correspondence (which is a sad jumble of misdates and opacities, in the common editions), [Preuss (the recent latest Editor, and the only well-informed one, as we said) prints with accuracy; but cannot be read at all (in the sense of UNDERSTOOD) without other light.] this of the aguish condition frequently turns up; "Quartan ague," it seems; occasionally very bad; but Friedrich struggles with it; will not be cheated of any of his purposes by it.

He had a busy fortnight here; busier than we yet imagine. Much employment there naturally is of the usual Inspection sort; which fails in no quarter of his Dominions, but which may be particularly important here, in these disputed Berg-Julich Countries, when the time of decision falls. How he does his Inspections we know; -- and there are still weightier matters afoot here, in a silent way, of which we shall have to speak before long, and all the world will speak. Business enough, parts of it grave and silent, going on, and the much that is public, miscellaneous, small: done, all of it, in a rapid-punctual precise manner; -- and always, after the crowded day, some passages of Supper with the Sages, to wind up with on melodious terms. A most alert and miscellaneously busy young King, in spite of the ague.