Objective appraisal of the outcome of the debate between Berkeley and
Mandeville would presumably lead to a verdict somewhere between those
rendered, with appropriate loyalty to their authors, by their
respective editors. It is mainly for other reasons, however, that the
_Letter to Dion_ is still of interest. There is first its literary
merit. More important, the _Letter_ presents in more emphatic and
sharper form than elsewhere two essential elements of Mandeville's
system of thought, the advocacy, real or pretended, of unqualified
rigorism in morals, and the stress on the role of the State, of the
"skilful Politician," in evoking a flourishing society out of the
operations of a community of selfish rogues and sinners. The remainder
of this introduction will be confined to comments on these two aspects
of Mandeville's doctrine. Since the publication in 1924 of F. B. Kaye's
magnificent edition of _The Fable of the Bees_, no one can deal
seriously with Mandeville's thought without heavy reliance on it, even
when, as is the case here, there is disagreement with Kaye's
interpretation of Mandeville's position.

It was Mandeville's central thesis, expressed by the motto, "Private
Vices, Publick Benefits," of _The Fable of the Bees_, that the
attainment of temporal prosperity has both as prerequisite and as
inevitable consequence types of human behavior which fail to meet the
requirements of Christian morality and therefore are "vices." He
confined "the Name of Virtue to every Performance, by which Man,
contrary to the impulse of Nature, should endeavour the Benefit of
others, or the Conquest of his own Passions out of a Rational Ambition
of being good."[8] If "out of a Rational Ambition of being good" be
understood to mean out of "charity" in its theological sense of
conscious love of God, this definition of virtue is in strict
conformity to Augustinian rigorism as expounded from the sixteenth
century on by Calvinists and, in the Catholic Church, by Baius,
Jansenius, the Jansenists, and others. Mandeville professes also the
extreme rigorist doctrine that whatever is not virtue is vice: in
Augustinian terms, _aut caritas aut cupiditas_. Man must therefore
choose between temporal prosperity and virtue, and Mandeville insists,
especially in the _Letter to Dion_, that on his part the choice is
always of virtue:

... the Kingdom of Christ is not of this World, and ... the
last-named is the very Thing a true Christian o