In Paradise Lost, it is Satan who takes the Prohibition to mean that

Citing Paradise Lost (or any long work with books, cantos, etc.)
 Remember to include on your Works Cited page the edition of the work that you are
using.
 Remember to cite poetry by line numbers. Since line numbering restarts with each
Book of Paradise Lost, it may be necessary to include the book number in your
citation also, unless it is clear from the context what book you are in.
In Paradise Lost, it is Satan who takes the Prohibition to mean that “Knowledge [is]
forbidd’n” and that it is “sin to know” (4.515, 517) and who assumes that the rule prevents
development, being “invented with design / To keep them low whom Knowledge might
exalt / Equal with Gods” (4.524-26). He succeeds in persuading Eve that the injunction is
unjust and therefore not to be obeyed: “what forbids he but to know,” she concludes
moments before taking the fatal bite, “Forbids us good, forbids us to be wise? / Such
prohibitions bind not” (9.758-60). But Milton himself elsewhere suggests that it is even now
possible for “virtue” to “know . . . the utmost that vice promises to her followers, and reject
[it],” that it is possible to “see and know and yet abstain” (Areopagitica, 728-9).
If you want to quote from the prose summary at the beginning of a Book (called the
argument), you can use the abbreviation arg. “Satan now in prospect of Eden . . . falls
into many doubts with himself” (4.arg.).