The one bit in here I remember seeing in one of the other versions (but I forget which one) was when Jekyll argues that man's "inherent sense of morality" does not "come from God" was was rather "mutually agreed upon"-- then throws out, "But what I DON'T agree?"
Interesting notion. But Laws are by agreement and not inherent, bogus hypocritical morality is a construct of societies and never becomes universal, inherent revulsion towards some particularly vile actions (child molestors etc, matricide, the worst crimes against persons) are not constructions of society. In those instances laws are constructed to deal with something that would otherwise be dealt with by the raw violence of outraged individuals.
From Corpus Juris Civilus "the Justinian Code"
How do Natural Law, Law of Nations, and Civil Law work together to create a legal system?
"Civil law is thus distinguished from the law of nations. Every community governed by laws and customs uses partly its own law, partly laws common to all mankind. . . . The people of Rome, then, are governed partly by their own laws, and partly by the laws which are common to all mankind."
"{N]ations have established certain laws, as occasion and the necessities of human life required. Wars arose, and in their train followed captivity and then slavery, which is contrary to the law of nature; for by that law all men are originally born free. Further, by the law of nations almost all contracts were at first introduced, as, for instance, buying and selling, letting and hiring, partnership, deposits, loans returnable in kind, and very many others."
"The laws of nature, which all nations observe alike, being established by a divine providence, remain ever fixed and immutable. But the laws which every state has enacted, undergo frequent changes, either by the tacit consent of the people, or by a new law being subsequently passed."
So Slavery which is patently immoral and a violation of natural law is a construct of society, an Immoral act sanctioned by a society for its own convenience. Legality does not equal Morality.