Conscience is the faculty by which we perceive fitness or unfitness. Its functions are not cognitive, but judicial. Its decisions are based upon our knowledge, real or imagined, from whatever source derived. It judges according to such law and evidence as it has; and its verdict is always, relatively, a genuine _verdict_ (_verum dictum_), though potentially false and wrong by defect of our knowledge,--even as in a court of law an infallibly wise and incorruptibly just judge may pronounce an utterly erroneous and unjust decision, if he have before him a false statement of facts, or if the law which he is compelled to administer be unrighteous. What we call the education of conscience is merely the accumulation and verification of the materials on which conscience is to act; in fine, the discovery of fitnesses. Permit me to illustrate the function of conscience by reference to a question now mooted in our community,--the question as to the moral fitness of the temperate use of fermented liquors. Among the aborigines of Congo and Dahomey, there being no settled industry, no mental activity, and no hygienic knowledge as to either body or mind, it seems fitting, and therefore right, to swallow all the strong drink that they can lay their hands upon; for it is fitted to produce immediate animal enjoyment,--the only good of which they have cognizance. Among civilized men, on the contrary, intoxication is universally known to be opposed to the fitnesses of body and mind, an abuse of alcoholic liquors, and an abuse of the drinker's own personality; and it is therefore condemned by all consciences, by none more heartily than by those of its victims. But there still remains open the question as to the moderate use of fermented liquors; and this is not, as it is commonly called, a question of conscience, but a mere question of fact,--of fitness or unfitness. Says one party, "Alcohol, in every form, and in the least quantity, is a virulent poison, and therefore unfit for body and mind." Says the other party, "Wine, moderately used, is healthful, salutary, restorative, and therefore fitted to body and mind." Change the opinion of the latter party, their consciences would at once take the other side; and, if they retained in precept and practice their present position, they would retain it self-condemned. Change the opinion of the former party, their consciences would assume the ground which they now assail. Demonstrate to the whole community--which physiology may one day do--the precise truth in this matter, there would remain no differences of conscientious judgment, whatever difference of practice might still continue.