Enthusiasm is always connected with the senses, whatever be the object that excites it. The true strength of virtue is serenity of mind, combined with a deliberate and steadfast determination to execute her laws. That is the healthful condition of the moral life; on the other hand, enthusiasm, even when excited by representations of goodness, is a brilliant but feverish glow which leaves only exhaustion and languor behind.

No state at war with another state should engage in hostilities of such a kind as to render mutual confidence impossible when peace will have been made.

[A ruler is merely] the trustee of the rights of other men and he must always stand in dread of having in some way violated these rights.

Reason can never prove the existence of God.

This spirit of freedom is expanding even where it must struggle against the external obstacles of governments that misunderstand their own function. Such governments are illuminated by the example that the existence of freedom need not give cause for the least concern regarding public order and harmony in the commonwealth. If only they refrain from inventing artifices to keep themselves in it, men will gradually raise themselves from barbarism.

But a lie is a lie, and in itself intrinsically evil, whether it be told with good or bad intents.

Time is not an empirical concept. For neither co-existence nor succession would be perceived by us, if the representation of time did not exist as a foundation a priori.