If first book of Wolff's Philosophia Practica Universalis was all about establishing the primary principle of practical philosophy, the second book, published year later than the first one, is then about application of this principle to more concrete cases. One must still remember that concreteness is here only a relative notion, and we are far from solving any determinate ethical or political questions.
The basic rules for good human action Wolff has already stated in the first book. One should follow natural law, which means striving for one's perfection. Since perfecting oneself means finding reliable and consistent happiness, natural law also guides us to strive for our own happiness. And, since God has made the world order, in which people become happy in certain manner, living according to natural law means also living according to God's decrees.
A new element in the second book is the social side of human activity. We are not just completely indifferent about each other's actions, but for instance, agree with other's actions, try to persuade them to some things etc. All these various social relations make responsibility of the actions also shared – if I convince my neighbour to do something, it is partially my fault, if something bad happens through her actions.
An important feature of this social element of human action Wolff emphasises is emulation – we tend to imitate behaviour of other people. This is important especially for making people act better. That is, if we set up examples of good life, heroes and saints, people might tend to improve their own live by imitating the lives of such good examples.
Wolff's suggestion that moral improvement might happen through emulation is an important sign of his appreciation of the less than fully intellectual side of human activity. True, Wolff thinks that one should try to improve one's behaviour through moral reasoning. Yet, he also sees that this is generally not enough, but there must be something to rouse the sensuous side of human mind. Thus, Wolff suggests that symbolism and rituals could be used for quickly teaching people about moral truths.
Despite admitting the importance of such sensuous element for morality, Wolff is still pretty antisensualist, when it comes to determining the actual principles of action. Senses and imagination provide us only with confused knowledge, which still requires conceptual analysis and reasoning to become truly valid and certain. Thus, sensuality as a source of confusion must be inhibited, in order to make oneself truly perfect.
Now, sensual side of human being is in Wolff's eyes not just a servant of morality or a mere hindrance to properly good life – it is also a sign of a person's motivation for his actions. Here Wolff once again speaks about physignomy, and since this is a topic I've discussed earlier I shall now merely mention it.
So ends Wolff's treatise on practical philosophy in general, although these outlines will be filled with more detailed treatises on ethics and politics later. But in case of theoretical philosophy, new personalities were already taking Wolff's formerly dominating place.