Page:William Petty - Economic Writings (1899) vol 1.djvu/72

lxiv of results, it is easy to find food for indulgent merriment in their crude apparatus. Not less amusing are their experiments with "a toad set in the middle of a circle of powder made with unicorne's horne," whose supposed charm it refused to recognize, incontinently hopping out of the circle again and again; or Sir Kenelm Digby's recommendation of "calcined powder of todes reverbrated applyed in bagges upon the stomach of a pestiferate body"—a pungent treatment of pestiferous bodies, whose obsolescence with the gradual mollification of social usages some will be found to regret. But the mere willingness to put the conduct of the toad to the test and to abide by the result argues confidence in the usefulness of experiment, and by implication in the uniformity of nature. It points the way to that precise knowledge of the world which alone can afford a firm foundation for invention and thus lead to the rule of man. It exhibits the Baconian rather than the Spinozistic sense of the maxim Knowledge is Power. It explains why the "Novum Organum" treats "De interpretatione naturæ sive de regno hominis." With the spirit of this philosophy Petty was strongly imbued. In a session of the Royal Society when some one chanced to use the words "considerably bigger," "Sir William Petty cautioned, that no word might be used but what marks either number, weight, or measure ." The caution may serve to indicate the nature of Bacon's influence over him. It was an influence exerted primarily upon Petty 's method, and only indirectly, through his method, upon the substance of his economic speculations.

In the field of his peculiar interests Petty sought the same quantitative precision which he demanded of his scientific colleagues. Now in economic investigation, as writers on the method of political economy never weary of iterating, the experimental method is in general precluded by the nature of the materials. The far seeing minister of an autocratic Czar may sometimes make industrial experiments on a gigantic scale and even isolate them from the disturbing influences of parliaments and newspapers, but he is not at all likely to utilize them for purposes of economic speculation. A favoured