Here’s one passage I remember after many years: Byron explaining how convenient it was for schoolboys that the editors of the classics had thoughtfully collected all the obscene bits in one place. They were too prudish to leave them in the text, but too scholarly to delete them altogether.

  Juan was taught from out the best edition,
    Expurgated by learnéd men, who place
  Judiciously, from out the schoolboy's vision,
    The grosser parts; but, fearful to deface
  Too much their modest bard by this omission,
    And pitying sore his mutilated case,
  They only add them all in an appendix,
  Which saves, in fact, the trouble of an index;

  For there we have them all "at one fell swoop,"
    Instead of being scatter'd through the Pages;
  They stand forth marshall'd in a handsome troop,
    To meet the ingenuous youth of future ages,
  Till some less rigid editor shall stoop
    To call them back into their separate cages,
  Instead of standing staring all together,
  Like garden gods—and not so decent either.

Only Cantos I and II were available in 1819.

XVI and unfinished XVII were available in 1823 and 1824 respectively.