He alleged, that fire was the sole vivifying principle that pervaded all nature; that, as the heat of the sun concocted the juice of vegetables, and ripened those fruits that grow upon the surface of this globe, there was likewise an immense store of central fire reserved within the bowels of the earth, not only for the generation of gems, fossils, and all the purposes of the mineral world, but likewise for cherishing and keeping alive those plants which would otherwise perish by the winter's cold. The existence of such a fire he proved from the nature of all those volcanoes, which in almost every corner of the earth are continually vomiting up either flames or smoke. "These," said he, "are the great vents appointed by nature for the discharge of that rarefied air and combustible matter, which, if confined, would burst the globe asunder; but, besides the larger outlets, there are some small chimneys through which part of the heat transpires; a vapour of that sort, I conceive, must pass through the bed or channel of this spring, the waters of which, accordingly retain a moderate warmth." This account, which totally overthrew the other's doctrine, was so extremely agreeable to the audience, that the testy doctor lost his temper, and gave them to understand, without preamble, that he must be a person wholly ignorant of natural philosophy, who could invent such a ridiculous system, and they involved in worse than an Egyptian fog, that could not at once discern its weakness and absurdity. This declaration introduced a dispute, which was unanimously determined in favour of our adventurer. On all such occasions the stream of prejudice runs against the physician, even though his antagonist has nothing to recommend himself to the favour of the spectators; and this decision depends upon divers considerations. In the first place, there is a continual war carried on against the learned professions, by all those who, conscious of their own ignorance, seek to level the reputation of their superiors with their own. Secondly, in all disputes upon physic that happen betwixt a person who really understands the art, and an illiterate pretender, the arguments of the first will seem obscure and unintelligible to those who are unacquainted with the previous systems on which they are built; while the other's theory, derived from common notions, and superficial observation, will be more agreeable, because better adapted to the comprehension of the hearers. Thirdly, the judgment of the multitude is apt to be biassed by that surprise which is the effect of seeing an artist foiled at his own weapons, by one who engages him only for amusement.