Kant Passages: The Good, the Bad, and the Ugly

“Metaphysics" is the study of pure concepts as they relate to moral or physical experience. (Sparknotes)
INTERESTING
Only experience can teach what brings us joy. Only the natural drives for food, sex, rest, and movement, and (as our natural predispositions develop) for honor, for enlarging our cognition, and so forth, can tell each of us, and each only in his particular way, in what he will find those joys; and, in the same way, only experience can teach him the means by which to seek them. (9)
This makes a lot of sense. How else would you know what brings you pleasure without experiencing it? This means that experience is necessary in determining what brings great joy.
Right is therefore the sum of the conditions under which the choice of one can be united with the choice of another I accordance with a universal law of freedom. (24)
Right must be determined not only by yourself, but by those around you, and then by the world.
Virtue is the strength of a human being’s maxims in fulfilling his duty. (156)
As I understand it, the duty would be his morality, and virtues are the way in which the individual reaches that end.
Virtue is always in progress and yet always starts from the beginning. It is always in progress because, considered objectively, it is an ideal and unattainable, while yet constant approximation to it is a duty. (167)
Virtues are always changing because they require the approval of society. They are not stable. They change over generations. A person cannot build upon a virtue if it is not constant.
PUZZLING
The conformity of an action with the law of duty is its legality (legalitas); the conformity of the maxim of an action with a law is the morality (moralitas) of the action. A maximum is a subjective principle of action, a principle which the subject himself makes his rue (how he wills to act). (17)
I need more explanation of this passage. How does this work?
Laws proceed from the will, maxims from choice. (18)
Don’t laws proceed from choice also? Don’t you choose whether you follow a law or not? I am confused with this rationale.
Freedom (independence from being constrained by another’s choice), insofar as it can coexist with the freedom of every other in accordance with a universal law, is the only original right belonging to every man by virtue of his humanity. (30)
Didn’t the other philosopher (like Hume) believe this to be otherwise? Doesn’t Hume believe that this is an artificial virtue? How is this original? Don’t you need someone to constrain you before you seek freedom?
…if the law can prescribe only the maxim of actions, not actions themselves, this is a sign that it leaves a playroom for free choice in following the law, that is, that the law cannot specify precisely in what way one is to act and how much one is to do by the action for an end that is also a duty. (153)
Huh? I do not see how the law does not specify how one is supposed to act. Doesn’t the law lay out specifics? Maybe I just do not understand what he is saying.