3. It is one thing to possess a speculative knowledge of human nature, to know the essence of the human being, which remains unchanged throughout the divers states of which this nature is capable (this despite the fact that in the state of fallen nature, even after having been restored by grace, it remains "wounded," weakened in its liberty and salutary forces, but given new strength by contact with other wounds, in this instance sacred); it is quite another thing to have the practical science of the conduct of man in the state of pure nature.

I do not think natural ethics is such practical science; it would be or would become such (by being organized and completed along other lines) if man were in the state of pure nature. In real fact, it is the ensemble (neither completely nor organically constructed even insofar as just natural) of practical truths or ethical truths which depend on the sole consideration and the sole exigencies of man's essence. It is for this reason essentially incomplete;^{6} for it is not the human essence which acts, but man in the concrete, who is known as such only on condition that both his essence and his existential conditions are known.

{6} Below the infused theological and cardinal virtues, for example, are the acquired cardinal virtues with a naturally knowable formal object and rule. Thus, acquired natural prudence proceeds by the light of the principles of natural reason, i.e., practical principles which are known by synderesis, such as: we must do good and avoid evil, we must be just, and so on.

However, as I already pointed out in the preceding note, without charity this natural acquired prudence and other cardinal virtues can exist only as dispositions and not as virtues strictly speaking. As a result, without charity they do not achieve a mutual connection, nor become bound in a single, strong organism, for such a connection is achieved only in statu virtutis. (Cf. St. Thomas and his commentators on this subject.) So the purely philosophic knowledge of these virtues remains something partial relative to moral science taken in its fullest sense, and is impotent to form by its own powers a complete and organically coherent doctrine of the virtues and of conduct.