Joseph Priestley, in particular, gave up with willingness to mankind what was obviously meant for chemical science.

A few years previously Brown of the _Estimate_ had submitted a scheme for national education, in which the essential principle was Church control.

Priestley had answered him, and was encouraged by friends to expand his argument into a general treatise.

His _Essay on the First Principles of Government_ appeared in 1768; and, if for nothing else, it would be noteworthy because it was therein that the significance of the "greatest happiness principle" first flashed across Bentham's mind.

But the book shows more than this.
"I had placed," says Priestley with due modesty, "the foundation of some of the most valuable interests of mankind on a broader and firmer basis than Mr.Locke"; and the breadth and firmness are Rousseau's contribution.
Certainly we herein meet new elements.