Our inability upon all occasions to appreciate the efforts of nature in the cure of disease, must always render our notions, with respect to the powers of art, liable to numerous errors and multiplied deceptions. Nothing is more natural, and at the same time more erroneous, than to attribute the cure of a disease to the last medicine that had been employed; the advocates of amulets and charms[73] have even been thus enabled to appeal to the testimony of what they call experience, in justification of their superstitions; and cases which, in truth and justice, ought to be considered most lucky escapes, have been triumphantly pronounced as skilful cures; and thus have medicines and practitioners alike acquired unmerited praise, or unjust censure. Upon Mrs. Stephens offering her remedy for the stone to Parliament,[74] a committee of professional men was nominated to ascertain its efficacy; a patient with stone was selected, and he took the remedy; his sufferings were soon relieved, and upon examining the bladder in the usual way, no stone could be felt, it was therefore agreed that the patient had been cured, and that the stone had been dissolved; some time afterwards this patient died, and on being opened, a large stone was found in a pouch, formed by a part of the bladder, and which communicated with it. When the yellow fever raged in America, the practitioners trusted exclusively to the copious use of mercury; at first, this plan was deemed so universally efficacious, that in the enthusiasm of the moment, it was triumphantly proclaimed that death never took place after the mercury had evinced its effect upon the system: all this was very true, but it furnished no proof of the efficacy of that metal, since the disease, in its aggravated form, was so rapid in its career, that it swept away its victims long before the system could be brought under mercurial influence, while in its milder shape it passed off equally well without any assistance from art.