If we go back upon the whole of the ideas we have just briefly expressed, we shall see that at each of the steps we have taken there are always two contraries opposed the one to the other: _good_ and _evil_, _command_ and _prohibition_, _virtue_ and _vice_, _merit_ and _demerit_, _pleasure_ and _pain_, _reward_ and _punishment_. Human life presents itself, then, under two aspects. Man can choose between the two. This power is liberty. This choice is difficult and laborious; it exacts from us incessant efforts. It is for this reason that life is said to be a _trial_, and is often represented as a _combat_. It should therefore not be represented as a play, but rather as a manly and valiant effort. Struggle is its condition, peace its prize. Such are the fundamental ideas _morality_ has for its object, and of which it seeks, at the same time, both the principles and the applications. =2. What is morality? the object of morality.=--Morality may be considered as a _science_ or as an _art_. By science we understand a totality of truths connected with each other concerning one and the same object. Science has for its object proper, _knowledge_. By art we understand a totality of rules or precepts for directing activity towards a definite end; art has for its object proper, _action_. Science is _theoretical_ or _speculative_; art is _practical_. Morality is a science inasmuch as it seeks to know and demonstrate the principles and conditions of morality; it is an art inasmuch as it shows and prescribes to us its applications. As science, morality may be defined: science of _good_ or science of _duty_. As art, morality may be defined: the art of right living or the art of right acting. =3. Division of morality.=--Morality is divided into two parts: in one it studies principles, in the other, applications; in the one, _duty_; in the other, _duties_. Hence a _theoretical_ morality and a _practical_ morality. The first may also be called _general_ morality, and the second _particular_ morality, because the first has for its object the study of the common and general character of all our duties, and the other especially that of the particular duties, which vary according to objects and circumstances. It is in the first that morality has especially the character of science, and in the second, the character of art. =4. Utility of morality.=--The utility of moral science has been disputed. The ancients questioned whether virtue could be taught. It may also be asked whether it should be taught. Morality, it is said, depends much more upon the heart than upon the reasoning faculties. It is rather by education, example, habit, religion, sentiment, than through theories, that men become habituated to virtue. If this were so, moral science would be of no use.