Conscience is a means, not a source, of knowledge. It is analogous to sight and hearing. It is the power of perceiving fitness and unfitness. Yet more, it is consciousness,—a sense of our own personal relation to the fitting and the unfitting, of our power of actualizing them in intention, will, and conduct. It is in this last particular that man differs from the lower animals. They have an instinctive perception of fitness, and an instinctive impulse to acts befitting their nature. But no brute says to himself, “I am acting in accordance with the fitness of things;” while man virtually says to himself, in every act, “I am doing what it is fit for me to do,” or, “I am doing what it is unfitting for me to do.”

Conscience is a judicial faculty. Its decisions are based upon such knowledge as the individual has, whether real or imagined, and from whatever source derived. It judges according to such law and evidence as are placed before it. Its verdict is always [pg 042] relatively right, a genuine verdict (verum dictum), though, by the absolute standard of right, it may be wrong, through defect of knowledge,—precisely as in a court of law an infallibly wise and incorruptibly just judge may pronounce an utterly erroneous or unjust decision, if he have before him a false statement of facts, or if the law which he is compelled to administer be unrighteous.

We may illustrate the function of conscience by reference to a question now agitated in our community,—the question as to the moral fitness of the moderate use of fermented liquors. In civilized society, 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 whether entire abstinence from fermented liquors be a duty, and this is a question of fact. 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 [pg 043] ground which they now assail. Demonstrate to the whole community—as it is to be hoped physiology will do at no distant day—the precise truth in this matter, there would remain no difference of conscientious judgment, whatever difference of practice might still continue.

Conscience, like all the perceptive faculties, prompts to action in accordance with its perceptions. In this respect it differs not in the least from sight, hearing, taste. Our natural proclivity is to direct our movements with reference to the objects within the field of our vision, to govern our conduct by what we hear, to take into our mouths only substances that are pleasing to the taste. Yet fright, temerity, or courage may impel us to incur dangers which we clearly see; opiniativeness or obstinacy may make us inwardly deaf to counsels or warnings which we hear; and motives of health may induce us to swallow the most nauseous drugs. In like manner, our inevitable tendency is to govern our conduct by the fitness of things when clearly perceived; but intense and unrestrained appetite, desire, or affection may lead us to violate that fitness, though distinctly seen and acknowledged.

Men act in opposition to conscience only under immediate and strong temptation. The great majority of the acts of bad men are conscientious, but not therefore meritorious; for merit consists not in doing right when there is no temptation to evil, but in resisting temptation. But, as has been said, it is [pg 044] as natural, when there is no inducement to the contrary, to act in accordance with the fitness of things, as it is to act in accordance with what we see and hear. It is the tendency so to act, that alone renders human society possible, in the absence of high moral principle. In order to live, a man must so act with reference to outward nature; still more must he so act, in order to possess human fellowship, physical comfort, transient enjoyment, of however low a type; and the most depraved wretch that walks the earth purchases his continued being and whatever pleasure he derives from it by a thousand acts in accordance with the fitness of things to one in which he violates that fitness.

Conscience, like all the perceptive faculties, is educated by use. The watchmaker's or the botanist's eye acquires an almost microscopic keenness of vision. The blind man's hearing is so trained as to supply, in great part, the lack of sight. The epicure's taste can discriminate flavors whose differences are imperceptible to an ordinary palate. In like manner, the conscience that is constantly and carefully exercised in judging of the fit and the unfitting, the right and the wrong, becomes prompt, keen, searching, sensitive, comprehensive, microscopic. On the other hand, conscience, like the senses, if seldom called into exercise, becomes sluggish, inert, incapable of minute discrimination, or of vigilance over the ordinary conduct of life. Yet it is never extinct, and is never perverted. When roused to action, even in the most obdurate, it [pg 045] resumes its judicial severity, and records its verdict in remorseful agony.

Conscience is commonly said to be educated by the increase of knowledge as to the relations of beings and objects, as to the moral laws of the universe, and as to religious verities. This, however, is not true. Knowledge does not necessarily quicken the activity of conscience, or enhance its discriminating power. Conscience often is intense and vivid in the most ignorant, inactive and torpid in persons whose cognitive powers have had the most generous culture. Knowledge, indeed, brings the decisions of conscience into closer and more constant conformity with the absolute right, but it does not render its decisions more certainly in accordance with the relative right, that is, with what the individual, from his point of view, ought to will and do. It has the same effect upon conscience that accurate testimony has upon the clear-minded and uncorrupt judge, whose mind is not made thereby the more active or discriminating, nor his decision brought into closer accordance with the facts as they are presented to him. Knowledge is indeed an indispensable auxiliary to conscience; but this cannot be affirmed exclusively of any specific department of knowledge. It is true of all knowledge; for there is no fact or law in the universe that may not in some contingency become the subject-matter or the occasion for the action of conscience. Nothing could seem more remote from the ordinary field of conscience than the theory of planetary motion; [pg 046] yet it was this that gave Galileo the one grand opportunity of his life for testing the supremacy of conscience,—it may be, the sole occasion on which his conscience uttered itself strongly against his seeming interest, and one on which obedience to conscience would have averted the only cloud that ever rested on his fame.