The moral sense does not imply innate complex ideas of the several actions and their tendencies, which must be discovered by observation and reasoning; it is concerned only about inward affections and dispositions, of which the effects may be very various.

In closing this part of his subject, he considers that all that is needed for the formation of morals, has been given, because from the moral faculty and benevolent affection all the special laws of nature can be deduced.

But because the moral faculty and benevolence have difficulty in making way against the selfish principles so early rooted in man, it is needful to strengthen these foundations of morality by the consideration of the nature of the highest happiness.
With Chapter VI.

accordingly he enters on the discussion of Happiness, forming the second half of his first book.

The supreme happiness of any being is the full enjoyment of all the gratifications its nature desires or is capable of; but, in case of their being inconsistent, the constant gratification of the higher, intenser, and more durable pleasures is to be preferred.
In Chapter VII., he therefore directly compares the various kinds of enjoyment and misery, in order to know what of the first must be surrendered, and what of the second endured, in aiming at highest attainable happiness.