Virtue is always in progress, and yet always begins from the beginning. The former follows from the fact that, objectively considered, it is an ideal and unattainable, and yet it is a duty constantly to approximate to it. The second is founded subjectively on the nature of man which is affected by inclinations, under the influence of which virtue, with its maxims adopted once for all, can never settle in a position of rest; but, if it is not rising, inevitably falls; because moral maxims cannot, like technical, be based on custom (for this belongs to the physical character of the determination of will); but even if the practice of them become a custom, the agent would thereby lose the freedom in the choice of his maxims, which freedom is the character of an action done from duty.
The consciousness of an internal tribunal in man (before which “his thoughts accuse or excuse one another”) is conscience.
Every man has a conscience, and finds himself observed by an inward judge which threatens and keeps him in awe (reverence combined with fear); and this power which watches over the laws within him is not something which he himself (arbitrarily) makes, but it is incorporated in his being. It follows him like his shadow, when he thinks to escape. He may indeed stupefy himself with pleasures and distractions, but cannot avoid now and then coming to himself or awaking, and then he at once perceives its awful voice. In his utmost depravity, he may, indeed, pay no attention to it, but he cannot avoid hearing it.
Now this original intellectual and (as a conception of duty) moral capacity, called conscience, has this peculiarity in it, that although its business is a business of man with himself, yet he finds himself compelled by his reason to transact it as if at the command of another person. For the transaction here is the conduct of a trial (causa) before a tribunal. But that he who is accused by his conscience should be conceived as one and the same person with the judge is an absurd conception of a judicial court; for then the complainant would always lose his case. Therefore, in all duties the conscience of the man must regard another than himself as the judge of his actions, if it is to avoid self-contradiction. Now this other may be an actual or a merely ideal person which reason frames to itself. Such an idealized person (the authorized judge of conscience) must be one who knows the heart; for the tribunal is set up in the inward part of man; at the same time he must also be all-obliging, that is, must be or be conceived as a person in respect of whom all duties are to be regarded as his commands; since conscience is the inward judge of all free actions. Now, since such a moral being must at the same time possess all power (in heaven and earth), since otherwise he could not give his commands their proper effect (which the office of judge necessarily requires), and since such a moral being possessing power over all is called god, hence conscience must be conceived as the subjective principle of a responsibility for one’s deeds before God; nay, this latter concept is contained (though it be only obscurely) in every moral self-consciousness.