ysicaltendencies, for, he said, there are facts in our sciences that can only beexplained in that light. If, for instance, copper be placed in air orwater, there will be no result, but if a touch of some acid be added, itwill oxidize. The explanation is that "the acid provokes oxidation of themetal because it has an affinity for the oxide which tends to form." - amaterial fact most metaphysical in its production, and only explicablethereby....
