[W]hen the safety of a state depends on any man's good faith, and its affairs cannot be administered properly unless its rulers choose to act from good faith, it will be very unstable; if a state is to be capable of lasting, its administration must be so organized that it does not matter whether its rulers are led by reason or passion -- they cannot be induced to break faith or act badly. In fact it makes no difference to the stability of a state what motive leads men to conduct its affairs properly, provided that they are conducted properly. For freedom or strength of heart is a private virtue; the virtue of a state is stability.
[I]f human nature were such that men desired most what was most useful to them, there would be no need of artifice to promote loyalty and concord. But since, it is well known, human nature is very different, it is necessary to organize the state so that all its members, rulers as well as ruled, do what the common welfare requires whether they wish to or not; that is to say, live in accordance with the precept of reason, either spontaneously or through force or necessity. But this only happens when the administration is arranged so that nothing which concerns the common welfare is wholly entrusted to the good faith of any man.
I shall leave interpretation as an exercise for the reader.