The topics of which moral instruction treats are the duties of life. To teach the duties, however, we must adopt some system of classification. To which system shall we give the preference? The difficulty which we encountered at the outset seems to meet us here in a new guise.
For most if not all of the systems of classification commonly proposed are based upon some metaphysical theory or some theological doctrine. To adopt any one of these would be tantamount to adopting the theory or theology on which it is founded; would be equivalent to introducing surreptitiously a particular philosophy or creed into the minds of the pupils; and this would be a plain departure from the unsectarian principle to which we are pledged. Thus, Plato's fourfold division of the virtues into the so-called cardinal virtues of temperance, courage, justice, wisdom, is based on his psychology. Aristotle's division of the virtues into dianoetic and what he calls ethical virtues is clearly dependent on what may be termed Aristotle's intellectualism—i. e., the supreme importance which he assigns to the functions of the intellect, or νοὑς [Greek: noûs], in the attainment of the perfect life.
Kant's division of duties into complete and incomplete is an outgrowth of the ideas developed in his Critique of Pure Reason; the philosopher Herbart's fivefold classification reflects his metaphysical theory of reality; while the systems of ethical classification which are to be found in theological handbooks betray still more clearly the bias of their authors.
We can, I think, find a simple way out of this difficulty by proceeding in the following manner: Let us take for our guidance the objects to which duty relates, and disregard the sources from which it flows. It is conceded on all hands that every one is to himself an object of duty, that he has certain duties to perform with respect to himself, as, for instance, the duty of intellectual development; furthermore, that every person owes certain duties to his fellow-men generally, in virtue of the fact that they are human beings; again, that there are special duties which we owe to particular persons, such as parents, brothers, and sisters; finally, that there are certain duties, into which, so to speak, we are born, like the ones last mentioned, and others which we can freely assume or not, like the conjugal duties, but which, once assumed, become as binding as the former. Thus the very structure of human society suggests a scheme of classification. And this scheme has the advantage of being a purely objective one. It keeps close to the facts, it is in harmony with the unsectarian principle, and it is perfectly fair. It leaves the problem of first principles entirely untouched. That we have such duties to perform with respect to self and others, no one questions. Let philosophers differ as to the ultimate motives of duty. Let them reduce the facts of conscience to any set of first principles which may suit them. It is our part as instructors to interpret the facts of conscience, not to seek for them an ultimate explanation.
Let me briefly indicate how the different duties may be made to fall into line according to the plan of classification which has just been suggested. The whole field of duty may be divided into three main provinces:[5] those duties which relate to ourselves, those which we owe to all men, and those which arise in the special relations of the family, the state, etc.:
I. The Self-regarding Duties.
These may again be subdivided into duties relating to our physical nature, to the intellect, and to the feelings.
Under the head of physical duties belong the prohibition of suicide, and the duties of physical culture, temperance, and chastity.
Intellectual Duties.—Under this head may be ranged the duty of acquiring knowledge and the subsidiary duties of order, diligence, perseverance in study; while, for those who are beyond the school age, special stress should be laid on the duty of mental genuineness. This may be expressed in the words: To thine own mental self be true. Study thine own mental bent. Try to discover in what direction thy proper talent lies, and make the most of it. Work thine own mine: if it be a gold-mine, bring forth gold; if it be a silver-mine, bring forth silver; if it be an iron-mine, bring forth iron. Endeavor to master some one branch of knowledge thoroughly well. It is for thee the key which opens the gates of all knowledge. The need of general culture is felt by all, but the concentration of intellectual efforts on special studies is not inconsistent with it. On the contrary, special studies alone enable us to gain a foothold in the realm of knowledge. A branch of knowledge which we have mastered, however small, may be compared to a strong fortress in an enemy's country, from which we can sally forth at will to conquer the surrounding territory. Knowledge may also be likened to a sphere. From every point of the circumference we can, by persistent labor, dig down to the center. He who has reached the center commands the sphere.