By a concept of the practical reason I understand the idea of an object as an effect possible to be produced through freedom. To be an object of practical knowledge, as such, signifies, therefore, only the relation of the will to the action by which the object or its opposite would be realized; and to decide whether something is an object of pure practical reason or not is only to discern the possibility or impossibility of willing the action by which, if we had the required power (about which experience must decide), a certain object would be realized. If the object be taken as the determining principle of our desire, it must first be known whether it is physically possible by the free use of our powers, before we decide whether it is an object of practical reason or not. On the other hand, if the law can be considered a priori as the determining principle of the action, and the latter therefore as determined by pure practical reason, the judgement whether a thing is an object of pure practical reason or not does not depend at all on the comparison with our physical power; and the question is only whether we should will an action that is directed to the existence of an object, if the object were in our power; hence the previous question is only as the moral possibility of the action, for in this case it is not the object, but the law of the will, that is the determining principle of the action. The only objects of practical reason are therefore those of good and evil. For by the former is meant an object necessarily desired according to a principle of reason; by the latter one necessarily shunned, also according to a principle of reason.