considers as the essence of fever, may be excited in the body, he states “that the fevers thus produced are modified by the prevalence or putrefaction of one or other of the four humours of Hippocrates; that of the three kinds of intermittent the quotidian arises from the corruption of phlegm, the tertian from that of the yellow and the quartan from that of the black bile; that in whatever part of the body the heat begins it ultimately extends to the heart; that as soon as this happens the general commotion of the vessels commences, and that in this manner Nature is employed in exerting her powers, endeavouring to assimilate the good humours to the parts which are to be nourished and to expel the bad, but that if at any time Nature is unable to expel all the morbid humour either from its thickness, its abundance or its tenacity, or from some obstruction of the passages, or from her own want of power, it will necessarily undergo putrefaction, if it remain long in the body, and produce the most fatal effects unless it be expelled by the process of concoction.” And so many centuries after Galen wrote, Sydenham who brought to the study of medicine one of the most acute, upright and independent minds that ever adorned it, commences a work on fever, which for fidelity of observation, for graphic description, for accurate discrimination, for bold and yet cautious treatment, has been justly considered an almost perfect model, with the following extraordinary assumptions:— “That reason dictates that a disease is nothing else than Nature’s endeavour to thrust forth with all her might the morbific matter for the health of the patient; that seeing it has pleased God, the Governour of all things, so to constitute human nature that it may be fitted to receive the various impressions that come from abroad, it must necessarily be subject to many diseases; that these diseases proceed partly from particles of air ill agreeing with the body, which having once insinuated themselves into it, are mixed with the blood, and affect the whole with a morbific contagion; and partly from various ferments or putrefaction of humours which are detained in the body beyond due time, either because it was not able to digest them, on account of the incongruity of their quality, or to evacuate them on account of their bulk; that these circumstances being so nearly joined to the human essence that no man can clearly free himself from them, Nature provided for herself such a method and concatenation of symptoms as that she might thereby expel the peccant matter, which would otherwise ruin the whole fabric; that the plague, for instance, is nothing but a complication of symptoms by which Nature casts out the malignant particles, by imposthumes in the emunctories, or by some other eruptions, that were drawn in by the air; that the gout is nothing but Nature’s contrivance to purify the blood of old men, and to purge the