What happens when reason is perfect and perfectly controls the will?  It is clear from what has been said that all moral concepts have their seat and origin completely a priori in reason, and indeed

What happens when reason is perfect and perfectly controls the will?  

It is clear from what has been said that all moral concepts have their seat and origin completely a priori in reason, and indeed in the commonest human reason, just as in that which is speculative in the highest measure; that they cannot be abstracted from any empirical and hence merely contingent cognition; that their dignity to serve us as supreme practical principles lies just in this purity of their origin; that every time in adding anything empirical to them one takes away as much from their genuine influence and from the unlimited worth of actions; that it is not only a requirement of the greatest necessity for theoretical purposes, when only speculation counts, but also a matter of the greatest practical importance to draw its concepts and laws from pure reason, to set them forth pure and unmingled, indeed to determine the scope of this entire practical but pure rational cognition, i.e. the entire faculty of pure practical reason, and in so doing not – as speculative philosophy may well permit, indeed at times even finds necessary – to make its principles dependent on the 4:412 particular nature of human reason, but because moral laws are to hold for every rational being as such, already to derive them from the universal concept of a rational being as such, and in this way (as should be possible in this species of entirely separate cognitions) completely to set forth all moral science – which for its application to human beings needs anthropology – first independently of this as pure philosophy, i.e. as metaphysics; well aware that without being in its possession it would be futile, I do not say to determine precisely for speculative judging the moral element of duty in everything that conforms with duty, but impossible to found morals on their genuine principles even for the merely common and practical use, principally of moral instruction, and thereby to effect pure moral dispositions and to engraft them on people’s minds for the highest good of the world. However, in order to progress in this work by its natural steps not merely from common moral judging (which is worthy of great respect here) to philosophical, as has been done elsewhere, but from a popular philosophy – that goes no further than it can get by groping by means of examples – to metaphysics (which does not let itself be held back any further by anything empirical and, as it must survey the totality of rational cognition of this kind, perhaps goes up to ideas, where even examples desert usk), we must trace and distinctly present the practical rational faculty from its general rules of determination up to where there arises from it the concept of duty. Every thing in nature works according to laws. Only a rational being has the capacity to act according to the representation of laws, i.e. according to principles, or a will. Since reason is required for deriving actions from laws, the will is nothing other than practical reason. If reason determines the will without fail, then the actions of such a being that are recognized as objectively necessary are also subjectively necessary; i.e. the will is a capacity to choose only that which reason, independently of inclination, recognizes as practically necessary, i.e. as good. If, however, reason all by itself does not sufficiently determine the will, if it is also subject to subjective conditions (to certain incentives) that are not always in agreement with the objective ones; in 4:413 a word, if the will does not in itself completely conform with reason (as is actually the case with human beings), then actions objectively recognized as necessary are subjectively contingent, and the determination of such a will, in conformity with objective laws, is necessitation; i.e. the relation of objective laws to a will not altogether good is represented as the determination of the will of a rational being by grounds of reason, to which this will is not, however, according to its nature necessarily obedient. The representation of an objective principle in so far as it is necessitating for a will is called a command (of reason), and the formula of the command is called imperative. All imperatives are expressed by an ought, and by this indicate the relation of an objective law of reason to a will that according to its subjective constitution is not necessarily determined by it (a necessitation). They say that to do or to omit something would be good, but they say it to a will that does not always do something just because it is represented to it that it would be good to do it. Practically good, however, is what determines the will by means of representations of reason, hence not from subjective causes, but objectively, i.e. from grounds that are valid for every rational being, as such. It is distinguished from the agreeable, as that which influences the will only by means of sensation from merely subjective causes, which hold only for the senses of this or that one, and not as a principle of reason, which holds for everyone.*