Credulity has been justly defined, _Belief without Reason_. Scepticism is its opposite, _Reason without Belief_ and is the natural and invariable consequence of credulity: for it may be generally observed, that men who believe without reason, are succeeded by others whom no reasoning can convince; a fact which has occasioned many extraordinary and violent revolutions in the _Materia Medica_, and a knowledge of it will enable us to explain the otherwise unaccountable rise and fall of many useless, as well as important articles. It will also suggest to the reflecting practitioner, a caution of great moment, to avoid the dangerous fault imputed to Galen by Dioscorides, of ascribing too many and too great virtues to one and the same medicine. _By bestowing unworthy and extravagant praise upon a remedy, we in reality do but detract from its reputation,[36] and run the risk of banishing it from practice_; for when the sober practitioner discovers by experience that a medicine falls so far short of the efficacy ascribed to it, he abandons its use in disgust, and is even unwilling to concede to it that degree of merit to which in truth and justice it may be entitled; the inflated eulogiums bestowed upon the operation of _Digitalis_ in pulmonary diseases, excited, for a time, a very unfair impression against its use; and the injudicious manner in which the antisyphilitic powers of _Nitric Acid_ have been aggrandised, had very nearly exploded a valuable auxiliary from modern practice.
It is well known with what avidity the public embraced the expectations given by Stöerk of Vienna in 1760, with respect to the efficacy of _Hemlock_; every body, says Dr. Fothergill, made the extract, and every body prescribed it, but finding that it would not perform the wonders ascribed to it, and that a multitude of discordant diseases refused to yield, as it was asserted they would, to its narcotic powers, practitioners fell into the opposite extreme of absurdity, and declaring that it could do nothing at all, dismissed it at once as inert and useless. Can we not then predict the fate of the _Cubebs_, which has been lately restored to notice with such extravagant praise and unqualified approbation? May the sanguine advocates for the virtues of the Colchicum derive a useful lesson of practical caution from these precepts: it would be a matter of regret that a remedy which, under skilful management, certainly possesses considerable virtue, should again fall into obscurity and neglect from the disgust excited by the extravagant zeal of its supporters.