By primacy between two or more things connected by reason, I understand the prerogative, belonging to one, of being the first determining principle in the connection with all the rest. In a narrower practical sense it means the prerogative of the interest of one in so far as the interest of the other is subordinated to it, while it is not postponed to any other. To every faculty of the mind we can attribute an interest, that is, a principle, that contains the condition on which alone the former is called into exercise. Reason, as the faculty of principles, determines the interest of all the powers of the mind and is determined by its own. The interest of its speculative employment consists in the cognition of the object pushed to the highest a priori principles: that of its practical employment, in the determination of the will in respect of the final and complete end. As to what is necessary for the possibility of any employment of reason at all, namely, that its principles and affirmations should not contradict one another, this constitutes no part of its interest, but is the condition of having reason at all; it is only its development, not mere consistency with itself, that is reckoned as its interest. If practical reason could not assume or think as given anything further than what speculative reason of itself could offer it from its own insight, the latter would have the primacy. But supposing that it had of itself original a priori principles with which certain theoretical positions were inseparably connected, while these were withdrawn from any possible insight of speculative reason (which, however, they must not contradict); then the question is: Which interest is the superior (not which must give way, for they are not necessarily conflicting), whether speculative reason, which knows nothing of all that the practical offers for its acceptance, should take up these propositions and (although they transcend it) try to unite them with its own concepts as a foreign possession handed over to it, or whether it is justified in obstinately following its own separate interest and, according to the canonic of Epicurus, rejecting as vain subtlety everything that cannot accredit its objective reality by manifest examples to be shown in experience, even though it should be never so much interwoven with the interest of the practical (pure) use of reason, and in itself not contradictory to the theoretical, merely because it infringes on the interest of the speculative reason to this extent, that it removes the bounds which this latter had set to itself, and gives it up to every nonsense or delusion of imagination?