We may divide pestilences into two classes: those which, as if dependent upon some noxious property of the air, have spread successively from country to country and devastated a large portion of the world, and those which have raged in a particular spot or within small limits, and which appear therefore to have been generated by some local accident, as is said to have occurred in Africa, B.C. 126 (A.U. 628), by the fetid exhalations from dead locusts,[94] or to have been introduced from other places, and to have been propagated rather by infection than the transmissive qualities of the air. To ascertain the specific difference between the two is probably beyond the reach of medical science; but the distinction is important, since the latter are susceptible of control by quarantine laws, which are powerless, perhaps worse than powerless, to arrest the former. Of these the most celebrated are quaintly described in a manuscript account of the great plague of London, preserved in the British Museum.[95] “Of universall, or œcumenicall[96] plauges, the most spreading and destructive that I have met with in history are these four: ffirst that of Athens, which fell out in the Peloponnesian warr, before Christ 428, described most fully by that eminent historian, Thucydides, in his second booke, who had been sicke of it himselfe, but restored, and from him by that great promoter and enlightener of the Epicurean, or Corpuscular Philosophy, the poet Lucretius, in the last part of his last booke. This plauge, though it bee vulgarly called the Athenian plauge, because it did great execution there in that city, yet indeed not on Athens alone, but as Thucydides tells us, beginning at Æthiopia overran Afrika and transferred itself into Asia, and thence into Europe.