Man can, indeed, act contrarily to the decrees of God, as far as they have been written like laws in the minds of ourselves or the prophets, but against that eternal decree of God, which is written in universal nature, and has regard to the course of nature as a whole, he can do nothing.

True virtue is life under the direction of reason.

Everything great is just as difficult to realize as it is rare to find.

Freedom is absolutely necessary for the progress in science and the liberal arts.

He alone is free who lives with free consent under the entire guidance of reason.

Laws which can be broken without any wrong to one's neighbor are a laughing-stock; and such laws, instead of restraining the appetites and lusts of mankind, serve rather to heighten them. Nitimur in vetitum semper, cupimusque negata [we always resist prohibitions, and yearn for what is denied us].

Whatever increases, decreases, limits or extends the body's power of action, increases decreases, limits, or extends the mind's power of action. And whatever increases, decreases, limits, or extends the mind's power of action, also increases, decreases, limits, or extends the body's power of action.