We have seen that _practical_ morality or _private_ morality has for its object to acquaint us with the _application_ of theoretical morality. It bears not so much on _duty_ as on _duties_. The first question, then, that presents itself to us is that of the _division of duties_. =17. Division of duties.=--It has been reasonably asserted that there is in reality but one duty, which is to do good under all circumstances, the same as it has also been said that there is but one virtue: wisdom, or obedience to the laws of reason. But as these two general divisions teach us in reality nothing touching our various actions, which are very numerous, it is useful and necessary to classify the principal circumstances in which we have to act, in order to specify in a more particular manner wherein the general principle which commands us to do good may be applied in each case. Human actions may then be divided, either in regard to the different beings they have for their object, or in regard to the various faculties to which they relate. The ancients divided morality particularly in reference to the divers human _faculties_, and in private morality they considered above all the _virtues_. The moderns, on the other hand, have divided morality particularly in its relations to the different _objects_ of our actions; and, in private morality, they have considered, above all, the _duties_. The ancients reduced all virtues to four principal ones: _prudence_, _temperance_, _courage_, and _justice_. This division was transmitted to us, and it is these four virtues which the catechism teaches under the name of _cardinal_ virtues. The moderns reduced duties to three classes: the duties towards _ourselves_, towards _others_, and towards _God_. Some add a fourth class, namely, duties towards _animals_. That portion of morality which treats of the duties towards ourselves, is called _individual_ morality; that which treats of the duties towards God, is called _religious morality_; that which treats of the duties towards other men, _social morality_. As to the duties towards animals, they are of so secondary an order, that it is not worth while to classify them apart; we shall include them in social morality. Social morality is by far the most extended in precepts and applications, the various relations of men with each other being extremely numerous. It may be subdivided into three parts: 1, general duties of _social_ life, or morality _properly called social_; 2, duties towards the State, or _civil_ morality; 3, duties towards the family, or _domestic_ morality. We will begin with the study of social morality, social duties towards men in general, and we will first establish their principles and different varieties. Let us in a few pages rapidly take a summary review of the general principles of _social_ morality.