If it had been merely the typhus of a hard winter, of overcrowding indoors, of work and wages stopped by the frost, and of want of fuel (which things Evelyn mentions as matters of fact), it would have come sooner than the spring of 1685. The Bills for years before have regularly a good many deaths from fever, and always some from spotted fever; but these may have come from parishes wholly beyond the range of Sydenham’s practice. The fever began definitely for him in February, 1685, and was at its worst in the old plague-seasons of summer and autumn. If the seasons had any relation at all to it, the epidemic was a late effect of the long drought, an effect which was manifested most when the rain came, in the summer of 1685 and throughout the mild winter and normal summer of 1685-86. It must have been for that reason that Sydenham traced the source of it to “some secret and recondite change in the bowels of the earth,” rather than to a change in the sensible qualities of the air. One must ever bear in mind that the physicians of the Restoration gave no thought to insanitary conditions of living; in that respect the later Stuart period seems to have been behind the Elizabethan or even the medieval; we cannot err in assuming, behind all Sydenham’s speculative causes, a great deal of unwholesomeness indoors. Sydenham’s fullest reference to the subterranean sources of poisonous miasmata occurs in his tractate on Gout: “Whether it be that the bowels of the earth, if one may so speak, undergo various changes, so that by the accession of vapours exhaled therefrom the air is disturbed, or that the whole atmosphere is infected by a change which some peculiar conjunction of certain of the heavenly bodies induces in it;--the matter so falls out that at this or that time the air is furnished with particles that are adverse to the economy of the human body, just as at another time it is impregnated with particles of a like kind that agree ill with the bodies of some species of brute animals. At these times, as often as by inspiration we draw into the naked blood miasmata of this kind, noxious and inimical to nature, and we fall into those epidemical diseases which they are apt to produce, Nature raises a fever,--her accustomed means of vindicating the blood from some hostile matter. And such diseases are commonly called _epidemical_; and they are short and sharp because they have thus a quick and violent movement[39].” It was Sydenham’s intimate friend Robert Boyle who worked out the hypothesis of subterraneous miasmata as a cause of epidemic (and endemic) diseases. An account of his theory will be found in the chapter on Influenzas and Epidemic Agues. It may be said here that it needs only a few changes, especially the substitution of organic for inorganic matters in the soil, to bring it into line with the modern doctrine of miasmatic infective disease as expounded by the Munich school.