if they succeeded, would be to set silver in the place gold now occupies. Every one should try to do something new. The world is already filled with transcriptions of work already done. An ordinary trade education only teaches men how to supplant one another. The true politics is how to preserve the subject in peace and plenty. The foundation of this science is to understand each country according to its natural divisions. Both trade and government might be made certain if such statistical information as the "Bills" contain could be made use of and its application extended. If such facts were known it would appear how few are engaged on necessary labors, how many do nothing, and are "mere gamesters by trade," how many live by puzzling others with "unintelligible notions in divinity and philosophie," how many by fighting, how many by trades of pleasure or ornament, how few "in raising and working necessary food," how few study nature and things. A clear knowledge of all these matters is, above all things, "necessary to a good, certain and easy government."
The work was enlarged in 1665 by the insertion of two new country bills; by some remarks on the Dublin bills; by actual enumeration of certain districts in London; by observations on foreign cities. After Graunt's death in 1673, the fifth edition was published by Petty in 1676, with two or three pages on the bills of foreign cities added.
Petty continued these investigations by publishing in 1682 his essay on the growth of London. Here he limits himself to ascertaining solely the population of London. He uses the mortality tables—adopting the old ratio of one death in thirty—
