Book II. is a deduction of the more special laws of nature and duties of life, so far as they follow from the course of life shown above to be recommended by God and nature as most lovely and most advantageous; all adventitious states or relations among men aside.  The three first chapters are of a general nature.

In Chapter I., he reviews the circumstances that increase the moral good or evil of actions.  Virtue being primarily an affair of the will or affections, there can be no imputation of virtue or vice in action, unless a man is free and able to act; the necessity and impossibility, as grounds of non-imputation, must, however, have been in no way brought about by the agent himself.  In like manner, he considers what effects and consequents of his actions are imputable to the agent; remarking, by the way, that the want of a proper degree of good affections and of solicitude for the public good is morally evil.  He then discusses the bearing of ignorance and error, vincible and invincible, and specially the case wherein an erroneous conscience extenuates.  The difficulty of such cases, he says, are due to ambiguity, wherefore he distinguishes three meanings of Conscience that are found, (1) the moral faculty, (2) the judgment of the understanding about the springs and effects of actions, upon which the moral sense approves or condemns them, (3) our judgments concerning actions compared with the law (moral maxims, divine laws, &c.).

In Chapter II., he lays down general rules of judging about the morality of actions from the affections exciting to them or opposing them; and first as to the degree of virtue or vice when the ability varies; in other words, morality as dependent on the strength of the affections.  Next, and at greater length, morality as dependent on the kind of the affections.

Here he attempts to fix, in the first place, the degree of benevolence, as opposed to private interest, that is necessary to render men virtuous, or even innocent, in accordance with his principle that there is implanted in us a very high standard of necessary goodness, requiring us to do a public benefit, when clear, however burdensome or hurtful the act may be to ourselves; in the second place, the proportion that should be kept between the narrower and the more extensive generous affections, where he does not forget to allow that, in general, a great part of human virtue must necessarily lie within the narrow range.  Then he gives a number of special rules for appreciating conduct, advising, for the very sake of the good to others that will result therefrom, that men should foster their benevolence by the thought of the advantage accruing to themselves here and hereafter from their virtuous actions; and closes with the consideration of the cases wherein actions can be imputed to other than the agents.