An easy explanation of plague ceasing in London has long been current, and just because it is an easy explanation it will probably hold the field for many years to come. It is that the fire of 1666 burnt out the seeds of plague. Defoe, writing in 1723, ascribed this opinion to certain “quacking philosophers,” but he would hardly have said so if he could have foreseen the respectable authority for it in after times. The plague had ceased in most of its provincial centres after the Civil Wars, and in some of them, such as York, from as early a date as 1604. It ceased in all the principal cities of Western Europe within a few years of its cessation in London. In London itself it ceased after 1666, not only in the City which was the part burned down in September of that year, but in St Giles’s, where the Great Plague began, in Cripplegate, Whitechapel and Stepney, where it was always worst, in Southwark, Bermondsey and Newington, in Lambeth and Westminster. Nor can it be said that the City was the source from which the infection used to spread to the Liberties and out-parishes. All the later plagues of London, perhaps even that of 1563, began in the Liberties or out-parishes and at length invaded the City. The part of London that was rebuilt after 1666 contained many finer dwelling-houses than before, built of stone, with substantial carpentry, and elegantly finished in fine and rare woods. The fronts of the new houses did not overhang so as to obstruct the ventilation of the streets and lanes; but the streets, lanes, alleys and courts were somewhat closely reproduced on the old foundations. A side walk in some streets was secured for foot-passengers by means of massive posts, which, with the projecting signs of houses and shops, were at length removed in 1766. The improvements in the City after the fire were mostly in the houses of the richer citizens. The City was the place of residence of the rich, with perhaps as many poorer purlieus in close proximity as the residential districts of London now have. But four-fifths of London at the time of the fire were beyond the walls of the City. It is in these extramural regions that the interest mostly lies for epidemical diseases. They remain, says Defoe in 1723, “still in the same condition they were in before.” Unfortunately we know little of their condition, whether in the 17th century or in the 18th. But there must have been something in it most unfavourable to health; for we find from the Bills of Mortality that the cessation of plague made hardly any difference to the annual average of deaths, the increase of population being allowed for. This fact makes the disappearance of plague all the more remarkable. Fevers to the end of the 17th century.