(Canto 11, lines 79-84)
"Thine Ethics" are Aristotle's Nicomachean Ethics. Virgil keeps mentioning Aristotle's works in this way: later in this Canto we find "Philosophy" and "thy Physics". The theory of three types of moral transgressions is to be found in Book 7: "of moral states to be avoided there are three kinds -- vice, incontinence, brutishness". Incontincence refers to faults resulting from letting various passions take over one's being and to go about seeking things that are not in themselves blameworthy in an extreme manner. This is the lowest degree of sin, because it does not consciously aim at harming any other person, and circles 2-5 are filled with sinners of this kind.
However, exactly what "Malice, and insane Bestiality" should correspond to in Dante's hell has been a matter of debate. Does "malice" correspond to the fraudulent and treacherous in circles 8-9 and "bestiality" to the violent in circle 7? The exact same term, "malice" was used as late as line 22 of the same Canto to refer to any punishable sins in general. It may be that, since Dante's question concerns sinners outside the 7th circle, Virgil's answer simply correspondingly gives an explanation for them, and that further systematizing is unnecessary.