It is Kant's great service to moral science that he purified it of all Eudaemonism. With the ancients, Ethics was a doctrine of Eudaemonism; with the moderns for the most part it has been a doctrine of salvation. The former wished to prove that virtue and happiness are identical; but this was like having two figures which never coincide with each other, no matter how they may be placed. The latter have endeavoured to connect the two, not by the principle of identity, but by that of causation, thus making happiness the result of virtue; but to do this, they were obliged to have recourse to sophisms, or else to assume the existence of a world beyond any possible perception of the senses.

Among the ancients Plato alone forms an exception: his system is not eudaemonistic; it is mystic, instead.